Art by Alexander Vasiljev, Copyright © 2017


Saturday, October 28, 2017


read introduction here

Defining Body Parts

The main body parts are identified as follows: head is from mouth to the edge of the gill cover, body is from gill cover to the vent below tail. The environment and grooming techniques will have a big impact on developing ranchu head, body and tail.

For body part names please refer to this article.

Building Ranchu Foundation

There is an old Japanese saying “Good ranchu head is created before the color change”. For the head-growth to develop properly, it needs a good scull structure, as a foundation. A good foundation must be selected and formed in kuroko before the change of color. During this time it is important to achieve balanced Dragon or Lion Head (more about ranchu standards here). 

If any combination of head-growth below occurs, the head will appear unbalanced:
  • growth on the top of the head, no growth on the gill plates 
  • growth evenly develops over the entire head  
  • growth develops on cheeks and under eyes only 
Delays in water changes help to suppress active fish movement and aids in developing head-growth at an early stage.

To Promote Head-Growth Development

Food is very important in developing head-growth. Feeding protein reach diet is a must. Silkworms, earthworms, bloodworms (can be frozen) are all high in protein and effective. Genetic background is also important.

Suggestions on promoting head-growth development:
  • feed plankton, bloodworms, green water 
  • reduce water changes to suppress movement 
  • make sure the body develops properly 
Pond depth is not known to effect head-growth development. To develop a good ranchu, balancing of the whole body and head must be achieved, and not just the head-growth.

To Promote Funtan (cheeks)

Feeding bloodworm and green algae will help in developing funtan. Suppress movement by extending intervals between the water changes and raising ranchu in green water.

To Promote Body & Head Development

It is important to develop a good skeleton in kuroko before the color change. Good balance between the head and body is very important. Preference should be given to longer bodies with wide back and peduncle, which will balance well with the size of the head.

To make back wider and increase the width between the eyes:
  • feed enough 
  • use green water 
  • slightly increase the stocking density to suppress active movement 
Beware that with increased stocking density vertical body growth will be suppressed.

How to Make Good Back

Water depth is very important in formation of a good back shape in fry. There is an old Japanese saying “Shallow water gives gently curved back, deep water gives round back” makes a good point. 

Water depth at 4 in (10cm) during the fry development produces gently curved back, while water depth around 3.3 ft (1m) gives more rounded shape. Genetics are also important in developing the right back.

Tail Tension

Tail shape is very important and is greatly dependent on grooming technique. However, if you only pursue creating a good tail, you will loose on fish health and overall quality. It is a trade-off to make a good tail and to keep fish health. It is difficult to do and one has to find a balance.

Factors that loosen tail tension:
  • weak tail shoulders 
  • excessive exercise 
  • large pond size
  • pond with no shade or over shaded 
  • strong aeration 
  • often water changes 
  • appropriate or slightly lower stocking density 
Factors that improve tail tension:
  • strong tail shoulders 
  • less exercise 
  • small pond size
  • pond with sun/shade balance 
  • weak aeration 
  • use of green water 
  • high or low stocking density 

Making a Good Tail Before the Color Change

To create a good tail, you must select kuroko with tail shoulders that are open at 160-180° and have a strong tail core.


To make a tail shoulder curve like in a bow (bow and arrow), the fish must swim moderately to finish formation before the color change. If the curve increases it may result in weak tension and possible collapse of the tail shoulders.

Making the Tail Core

Water depth will effect the tail core in fry. The depth at 4 in (10cm) during development is necessary. There is a tendency for the tail core either to fall lower if the water depth is too shallow or rise up if the depth is too deep.

After the tail is formed and the core is established in kuroko stage, it is not effected as much by the water depth. Still, as a general rule, it is a good idea to keep the water depth at 6-8 in (15-20cm) during ranchu development. Also, increased exercise may result in softening of the tail core, as well as loss of the tail tension.

Monday, October 16, 2017


read introduction here

Keep A Diary

Write down everything that has to do with breeding and progress of your ranchu. Documenting when and what is a good practice and creates an important database for your future reference.

Water Temperature During Hatching

68 F (20°C) is optimal water temperature for developing fertilized eggs. If the temperature is lover, fry will not hatch all at the same time and there will be a high percentage of malformed fish. Temperatures above 68 F (20°C) will induce egg development, resulting in higher percentage of tail regression to original "wild" carp. Controlling water temperature by shading and/or using a heater is necessary. 

Water temperature and timing from spawning till hatching:
  • 57 F (14°C) - hatching on the 7th day 
  • 61 F (16°C) - hatching on the 6th day 
  • 64 F (18°C) - hatching in 5 ½ days 
  • 68 F (20°C) - hatching on the 5th day 
  • 71 F (22°C) - hatching in 4 ½ days 
  • 75 F (24°C) - hatching on the 4th day 
Watch the water quality, as it can deteriorate quickly after spawning, due to unfertilized eggs and milt remains. It is best to transfer the eggs or change water right after spawning and keep the temperature constant at 68 F (20°C). In some cases, adding drops of methylene blue helps to prevent fungal growth on ranchu eggs.

Feeding The Fry

The fry are born with a yolk sac that provides them with nutrients for a couple of days. Start feeding the fry on the 2nd day after hatching. 

It is very important to provide enough food for the fry to keep up with their high growth rate. When feeding live food, the portion size is not important. The fry must eat as much as they need and any time they want. Digestion time is short. There should be a constant supply of live food, as it gets eaten from morning till evening. One of the most accessible live foods for fry is freshly hatched brine shrimp. Read more on brine shrimp here.

When feeding frozen food or micro pallets, the portion size need to be observed, as overfeeding can spoil the water fast. A single dose should be of what fry can eat in 5 min. Digestion time is longer. Intervals between feedings must reflect digestion times, but feeding must be preformed often.

Water Changes & Fry

It is very important to keep constant temperature during the water changes. Even small temperate fluctuations may weaken or kill very sensitive at this stage fry. Also, watch the aeration. Strong aeration can damage the fry, adequately adjust air pump pressure to minimize any water turbulence. 

Its best not to transfer very young fry during the water change, but scoop as much water as you can and replace it with fresh. When fry has grown a little it will handle the transfer better, still be very carful scooping it during the water change, to prevent any injury. At this time it is best to have two containers and alternate them during the water change.

Filamentous Green Algae & Fry

Due to higher stocking density and/or food left in the water, filamentous green algae or Spirogyra can grow very rapidly. This algae produces long hair-like strings and if eaten by fry will get stuck in their small bodies, coming out through the gills or vent. It can not be removed and will eventually kill the fry.

Adjusting stocking density, regular water changes and cleaning the container will keep it under control.

Growth Rate

Learn to determine proper stocking density. This will insure that the fry doesn’t die and will promote faster development. Balancing the amount of food and stocking density is important for a healthy development of the fry and to prevent a number of diseases.

It is important to make fry growing as fast as possible. For example, for the fish hatched in April, a goal would be to have the fish reaching 4 in (10 cm) in length by the fall. 

Growth rate of the fry indicating its healthy development:
  • 1st week - 3/8 in (10mm) 
  • 2nd week - 1/2 in (13 mm) 
  • 3rd week - 5/8 in (16 mm) 
  • 1st month - 6/8 in (20 mm) 
  • 7/8 in (22 mm) increase in the 2nd month - 1 5/8 in (42 mm) 
  • 1/2 in (13 mm) increase in the 3rd month - 2 1/8 in (55 mm) 
  • 5/8 in (15 mm) increase in the 4th month - 2 6/8 in (70 mm) 
  • 5/8 in (15 mm) increase in the 5th month - 3 3/8 in (85 mm) 
  • 1/2 in (12 mm) increase in the 6th month - 3 2/8 in (97 mm) 
  • 5/16 in (8 mm) increase in the 7th month - 4 1/8 in (105 mm) 
If you have achieved the above growth rates, look for more ways to improve. If you are behind these growth rates, increase one or all of the following: 
  • food amount 
  • water changes 
  • adjust stocking density

Effect of Stocking Density On Tosai Ranchu

Always pay attention to stocking density for the fry in its first year. High density will cause illness in fish and delays in development. During this period you want for the fish to grow lengthwise and loosen stiffness in their tails. Do regular water changes before water spoils. Regularly remove waist and uneaten food.

High Density:
movement is restricted, high probability of gill disease, growth is slow, rapid water quality deterioration, tail shoulders and core remain hard and make it difficult to swim

Somewhat Low Density:
water quality is maintained, chances of illness are low, growth is higher in width and normal in length, competitive spirit and appetite is good, only tail core softens.

Low Density:
water may deteriorate causing illness even though it looks clean, growth in length is much suppressed, vertical growth is slower. Due to lack of competition between the ranchu, their appetite is lower, they swim less and because of that both tail shoulders and core remains stiff

Appropriate Density:
water quality is maintained, growth is accelerated in both length and width, better appetite and good competitive spirit, swims more. Both tail shoulders and core softening which helps to swim better. Adjust stocking density by culling. It is important to identify quality ranchu as early as possible to maintain appropriate stocking density. 

Appropriate ranchu count per 3.3 ft² (1 m²) container that is 4 in (10 cm) gradually increasing to 10 in (25 cm) deep:
  • up to 0.6 in (1.5 cm) long fish - up to 100
  • 0.8 in (2 cm) long fish - up to 60
  • 1 1/8 in (3 cm) long fish - up to 50
  • 1 5/8 in (4 cm) long fish - up to 40
  • 2 3/8 in (6 cm) long fish - up to 20
  • 4 in (10 cm) long fish - up to 5 

Thursday, October 5, 2017


read introduction here

Choosing a Breeder Ranchu

There is on old Japanese saying in ranchu circles “Chose male ranchu for its good tale and female ranchu for its thick body and head”. Another old saying is “Choose ranchu with a good tail from the right environment”. 

A good tail of a first-class ranchu doesn’t only come from its genetic heritage. The environment, where the ranchu was raised will effect the tail quality and strength. The key is to combine a good genetic foundation with the right environment.

Grooming ranchu in the right environment will help to develop a great quality fish. It is not necessary to breed a show champion ranchu to get first-class offsprings. Raising fry with a perfect tail in a poor environment will not yield good results either.

A good tail is considered when the line in the center of the tail or tail core, or midrib (o-shin) is straight and extends outward firmly. Also, tail shoulders (o-gata) should be at 160-180° and not too stiff, but also not too soft. Please refer to "Defining What Is What" to identify ranchu body parts.

Mistakes Made In Selecting Seed Ranchu 

Tail shape is often overlooked and the preference is given to the head shape and overall looks while selecting a breeder fish.

The head shape and proportion to the rest of the body is important, but if you really want to breed a first-class ranchu, great attention must be given to choosing a good tail. That is where true art of ranchu breeding is.

Friday, September 29, 2017


read introduction here

Amount of Food & Water temperature

Ranchu's physiological functions are greatly affected by the ambient water temperature. It is very important to adjust food type and amount in accordance with the water temperature. If not fed correctly, ranchu might develop indigestion problems and their immune system may get weaken, making them prone to decease.

  • 32-43 F (0-6°C) - fish hibernate, no food is required
  • 44-54 F (7-12°C) - physiological functions are slow; give only small amount of easily digestible food
  • 55-64 F (13-18°C) - physiological functions are not to their fullest; increase the food amount carefully; use easily digestible food
  • 65-75 F (19-24°C) - fish is active, food amount must be increased 
  • 76-86 F (25-30°C)- very active growth; provide enough food, but watch for signs of obesity 
  • 87-97 F (31-36°C) - fish appetite is lower; provide appropriate amount of food
  • 98-100 F (37-38°C) - upper limit of water temperature for ranchu
  • above 100 F (38°C) - temperature is harmful for ranchu

Feeding Depends On the Weather & Seasons

Adjust amount of food according to the weather and season, especially for the fish kept outside. If the water temperature changes due to the air temperature drop or rain, reduce the amount of food. Feed 2 hrs before the rain forecast. When temperature rises back up, increase food amount.

During hot summer days feeding in the morning is preferable due to cooler water temperature. In colder seasons, when water temperature starts to drop in the afternoon, feeding late may cause indigestion. Suggested feeding times during the sunny weather for ranchu that are kept outside:

  • spring - from 7:30am till 3pm 
  • summer - from 6am to 4pm; watch for the rain that will lower water temperature; to make ranchu grow faster, give food 2 hrs before it gets dark. 
  • fall - from 7:30am till 3pm 
  • winter - at low temperatures no food is usually given; if given, should be around noon 

Amount of a Single Feeding

Ranchu has no stomach. In order to provide proper digestion time, the single food portion must be eaten within 5 min. Try to avoid food leftovers, as it will effect the water quality.

Number of Feedings

It is best to feed after previously given food has been digested. In the warm temperature you can feed as soon as previous food has been digested, up to five feedings per day for young fish, when a single portion can be eaten in 5 min. Remember different foods have different digestion times.

Feeding On the Day of Water Change

There is an old saying: “Refrain from food on the day of new water”. With a large water change the fish is stressed and its physical condition is weakened. 

“Refrain” however, doesn’t mean to completely avoid food. Right after the water change the fish' somatic nerve system is stimulated by the fresh water, making them more active. At the same time gastrointestinal function is reduced. After 30 minutes of fish being in the new water, somatic nerve system usually calms down, normalizing functions of gastrointestinal tract and releasing stress. At this time you can give a single portion.

When Fish is Not Eating

Not eating can be influenced by several factors. It is important to quickly determine what causes it and take an action:

  • fish condition - improve the way you feed, check for disease or start a treatment 
  • food quality - change the food type, change the way the food is stored 
  • water quality - watch for water quality deterioration, perform regular water changes 
  • environment - make sure water temperature is between 64-86 F (18-30°C), improve aeration and shading, adjust stocking density of the fish 

Prevention of Fish Obesity

  • moderate diet, restrain from giving too much food
  • let wall algae to grow, use green water 
  • balance wider variety of foods and use high quality pellets
  • extend interval between water changes
  • exercise fish, but care not to lose the tail tension and shape 
  • observe water temperature and seasons and adjust the food regiment accordingly
  • maintain appropriate stocking density to keep fish competitive 

Thursday, September 21, 2017


read introduction here

Ranchu are omnivores and prefer a wide variety of foods. To insure health and reduce obesity, their diet has to be balanced with proteins, carbohydrates, minerals and vitamins.

Foods high in protein:
  • live or frozen brine shrimp
  • daphnia
  • bloodworm
  • pellets

Foods high in vitamins and minerals:
  • algae
  • duckweed
  • chlorella and phytoplankton
  • spirulina
  • pumpkin
  • spinach
  • wolffia

Food Types And Digestion Times

Food with less moisture content takes longer to digest. A safe interval between feedings can be placed at 2 hours, however digestion time will change depending on the amount of food given. Approximate digestion times:
  • daphnia, brine shrimp, wolffia, duckweed - 1 hr
  • bloodworm - 1 ½ hr
  • pellets - 2 hrs. 


One of the foods that is central to ranchu development. Easily digestible and highly absorbent, daphnia is high in nutrients and contributes to a maximum fry growth potentials.


Another food that is very important to ranchu. It has superior digestion and absorption rate. High in protein, it promotes head-growth and overall development.

Brine Shrimp

With excellent absorption rate and nutritional value it is a good alternative to daphnia. Newly hatched brine shrimp is excellent for feeding fry.


Low in fat and protein, vegetables are rich in vitamins, minerals and organic pigments, and are very important supplement. They promote colors and overall health, especially at young stages. Most used vegetables are: phytoplankton, green algae, chlorerlla, spirulina, duckweed, pumpkin, wolffia and spinach among others.

Commercial Pellets

Due to low moisture content, digestion rate is the slowest, up to 2 hrs and more. Best if pellets are alternated with easily digestible foods, e.g. bloodworm. Due to high nutritional value and longer digestion times, feeding only with pellets may cause obesity and requires carful observation. There are many brands that offer ranchu pellets. However, not all of them are equal in quality and value. My own preference is Azayaka Brand ranchu pellets. Here is my article on different brands of pellets, their comparison and analyzes.


Organic pigments or carotenoids like luteins (for yellows) and astaxanthin (for reds) are very important for developing fish coloration. Incorporating spinach, pumpkin, duckweed, wolffia and color enhancing pellets is beneficial.


Wolffia is the world’s smallest flowering plant that belongs to a group of duckweeds. It is easily digestible, contributes to color development (especially yellow) and overall health of a young fish. It also helps to maintain a slim belly. Wolffia can be easily substituted with duckweed.

Benefits of Wolffia or Duckweed:
  • promotes head-growth development
  • promotes slim belly and good physical shape
  • easily digestible
  • rich in vitamins and minerals
  • high in protein
  • positively effects color development
  • shades the water and helps to lower water temperature
  • removes access of oxygen and supplies carbon dioxide
  • utilizes ammonia 

Cultivating Wolffia or Duckweed:
  • requires a lot of sunlight
  • tap water can be used
  • provide light aeration
  • will propagate very rapidly in 86 F (30°C)
  • keep water temperature under 97 F (36°C)
  • in winter, if temperatures are low, will go dormant and will sink to the bottom

Tuesday, September 19, 2017


read introduction here

Concrete Pond

Concrete has been a long time favorite material for building traditional ranchu ponds. Common sizes are 6.6 ft x 6.6 ft x 10in (2m x 2m x 25cm) and 5ft x 5ft x 10in (1.5m x 1.5m x 25cm). Square size is easy to arrange in succession, maintain and clean.

In the past, there was an indentation made on the bottom of the pond in the shape of a square, for collecting and removing of debris and for the fish to be kept during the water change. Also, there was a white tile placed on the bottom of the pond to determine translucency and color of the green water. However, nowadays, these features are not used.

Fiberglass or Polyethylene Pond

These materials are strong and durable and are commonly used in modern days and have good qualities for thermal insulation. Although, if the walls are too thin the pond might get deformed under the water weight.

Plastic Pond 

Any large plastic container, e.g. cement mixing tub or children’s pool, etc, can be used, as long as it's depth is between 9-12in (22 - 30cm). These containers are durable, cheap and come in different sizes, shapes and colors. Quite suitable for raising fry and young ranchu.

Pond Liner

It is a good option for DIY and can be used to create pond of any size and shape. Although, it is more prone to leaks.

Sunday, September 17, 2017


read introduction here


It is necessary to have at least 3 hours of sunlight a day. Sunlight is very important for a healthy ranchu and aids in brighter colors and it is instrumental for photosynthesizing phytoplankton and wall algae growth, sustaining healthy environment. As a positive side effect, sunlight's ultraviolet rays are anti-bactericidal. Watch for ranchu getting too stimulated by sunlight, as excessive swimming may weaken their tail tension, especially when young.


Strong direct sunlight can cause deterioration of ranchu physical condition and with water depth of only 6-10 in (15-25 cm) the pond can get easily overheated. It is important to shade the pond if water temperature rises near or above 86 F (30°C). However, avoid excessive shading, as it reduces the sense of seasons in ranchu.

Cheese cloth, synthetic shade cloth or bamboo/reed blinds can be used to shade the pond. It is suggested to position shading material 6.6 ft (2 m) above the water surface to provide sufficient ventilation and gas exchange.

Friday, September 15, 2017


read introduction here

Adequate aeration is important in supplying water with oxygen. It also aids in better water circulation and equalizes temperature between different layers in the pond. 

However, vigorous aeration can have a negative impact on developing ranchu, especially their tale formation. It is very important to bring aeration to its minimum or avoid it all together during eggs hatching and fry development and, when the tail starts to form and open.

Advantages of aeration:
  • supply of oxygen to the water 
  • release of carbon dioxide from the water 
  • mixes water for more uniform water temperature 
  • delays deterioration of the water quality 

Drawbacks of aeration:
  • too much aeration loosens the tail tension and effects its shape 

Oxygenation And Water Surface 

Pond surface is important for oxygenation. If covering or shading the pond, attention should be paid not to obstruct the airflow and gas exchange. It is necessary to provide good ventilation if the pond is inside or when air temperatures are high.

The Amount of Dissolved Oxygen And Water Temperature

There are two factors that effect how much oxygen is dissolved in the water: temperature and pressure.

With shallow pond used for ranchu, water pressure does not have much effect. The amount of dissolved oxygen will primarily depend on increase or decrease in temperature. As a rule, with temperature increase the amount of dissolved oxygen will proportionally decrease:

  • 32 F (0°C) - 14.16 ml/L 
  • 34 F (1°C) - 13.77 ml/L 
  • 41 F (5°C) - 12.37 ml/L 
  • 50 F (10°C) - 10.92 ml/L 
  • 59 F (15°C) - 9.76 ml/L 
  • 64 F (18°C) - 9.18 ml/L 
  • 68 F (20°C) - 8.84 ml/L 
  • 77 F (25°C) - 8.11 ml/L 
  • 86 F (30°C) - 7.53 ml/L 

In the summer, due to higher temperatures water oxygen levels are at their lowest. Ranchu requires more oxygen in the summer, as it is most active. If there is a lack of oxygen in the water, ranchu will be swimming “nose up” at the surface gasping for air. Sufficient aeration is required, as well as the appropriate stocking density.

Oxygenation And Green Water

Phytoplankton in green water photosynthesizes and supplies oxygen to the water. When water gets over saturated with dissolved oxygen, it starts to escape in the form of gas. So called “gas bubble disease” may occur, when oxygen gas bubbles appear in the fish bloodstream and become visible on gills, fins and eyes. It can cause a secondary infection or even be fatal.

When using green water, additional aeration may not be necessary. Still, keep an eye on oxygen level becoming too low.

Monday, September 4, 2017


read introduction here

Ranchu Body Temperature

Ranchu are ectothermic animals, which means their body temperature matches the temperature of the environment. They are also eurythermal, meaning that they are able to tolerate a wide range of temperatures. Depending on the environmental conditions, ranchu will adjust their metabolism.

Optimal temperature for ranchu active growth is between 64-86 F (18-30°C). As the water temperature rises above 86 F (30 C), ranchu activity becomes suppressed, negatively impacting their development. When the temperature drops below 64 F (18 C), ranch's metabolism begin to slow down. Below 43 F (6 C), ranchu enter a hibernation state. Cold temperatures, however, are part of ranchu's natural life cycle and are beneficial. As a temperate climate fish, ranchu enjoy all four seasons.

Temperature Fluctuations

Ranchu is adaptable to a wide temperature range, but only if the temperature changes gradually. It is best if the temperature increases no more then 1.8 F (1°C) degrees per day. A sudden increase of 9 F (5°C) degrees can be lethal, especially for fry and young fish. In an emergency, if the water temperature must be increased quickly, for disease treatment, it has to be done in increments of no more than 4-5 F (2-3°C) degrees per day until the desired temperature is reached. Decreasing the temperature is much better tolerated by the fish, but a gradual change is best.

It is important that the water temperature difference between early morning and noon fluctuates no more than 18 F (10 C) degrees. If it exceeds that - shading, ventilation or a bigger container is required.

Ranchu Activity & Water Temperature 

The range of water temperatures suitable for ranchu is between 30 and 100 F (-1 to +38°C). However, each temperature level dramatically effects the fish's physiology:
  • 32-43 F (0-6°C) - full hibernation state, ranchu are inactive
  • 44-54 F (7-12°C) - semi-hibernation, physiological functions are slow
  • 55-64 F (13-18°C) - intermediate state between hibernation and active state; physiological functions are not up to their fullest 
  • 65-75 F (19-24°C) - fish is ready to spawn, gonads develop; pathogens become more active 
  • 76-86 F (25-30°C) - active fish growth 
  • 87-97 F (31-36°C) - fish growth supressed 
  • 98-100 F (37-38°C) - upper water temperature limit for ranchu 
  • above 100 F (38°C) - temperature is NOT suitable for ranchu 

Use of Heater 

Although, a heater isn't necessary for day-to-day ranchu keeping, it might be useful in some situations. For the most part, breeders use it to adjust spawning time, to incubate ranchu eggs and to control the beginning stages of ranchu fry. A heater can also be used to aid in treating some diseases.

  • setting water temperature as desired 
  • controlling to big of a temperature fluctuation during the day 
  • to interrupt hibernation 
  • adjusting spawning season 
  • adjusting hatching date and promote fry growth 
  • increase disease treatment outcome 

  • difficult to keep the same water temperature during water changes 
  • lack of four season temperatures may lead to obesity 
  • temperatures that are kept the same, lead to more rapid water quality deterioration 
  • electrical bill

Friday, September 1, 2017


read introduction here

There is an old Japanese saying “Ranchu is made with green water”. When viewed under the microscope, green water is composed of plankton - microscopic animals, green algae, cyanobacteria (blue-green “algae”) and diatoms (brown-golden algae), which freely float in the body of water that is exposed to sunlight. Plankton is rich in protein, minerals and vitamins.

Green water isn't always used for ranchu, in fact, most modern ranchu keepers will not encourage green water. However, if the ranchu pond is exposed to bright sunlight (especially outdoors) and warm temperatures, it most likely will develop green water. If you decide to explore the green water method, then this chapter is for you.

The effects of green water on ranchu:
  • anorexigenic - fish has less appetite for additional food, due to constant feeding on plankton; reduce amount of given food 
  • motor inhabitory suppression - fish growth less lengthwise and tend to become rounder and bulkier 
  • green water holds temperature better with less fluctuation 
  • improves physical condition of the fish 
  • improves color of the fish

Color of Green Water
It takes experience to master green water. This method will require much more attention from the keeper to monitor the condition of water. There are two types of green water - green and brown in color, both have equal effect. Both types are often seen when the temperatures start to drop. The green or brown color of the water is determined by the balance of microorganisms.

Signs of Green Water Quality Deterioration

One of the signs of declining water quality is the formation of bubbles from aeration on the surface of the water. If the bubbles form a circle greater then 2 ft (60 cm) in diameter, it indicates that the water quality is deteriorating. When green water is used, one must observe how dark and opaque it gets. It must be kept similar to the transparency of Japanese green leaf tea (not matcha 抹茶 - ceremonial green tea). If green water suddenly changes in color or opacity, or CLEARS - 100% water change is necessary as soon as possible. Green water deterioration can occur rapidly and needs a quick response, or the fish will suffer. Overfeeding is often the cause of this. 

Signs of water deterioration:
  • aeration bubbles are spread over 2 ft (60 cm) in diameter 
  • green water darkens rapidly or clears 
  • fish develops gas bubbles disease

Green Water Changes 

Best if water change is done in the morning on a sunny day. If tap water is used, it needs to be conditioned before use.

Temperature and water change proportions of green and fresh water:
  • 32-54 F (0-12°C) - only replenish what was evaporated 
  • 55-64 F (13-18°C) - when water deteriorates, use half old and half fresh water 
  • 65-75 F (19-24°C) - when water deteriorates, use a little of old water and mostly fresh water 
  • 76-97 F (25-36°C) - when water deteriorates, change 100% for fresh water 
  • 98-100 F (37-38°C) - upper limit of the water temperature for ranchu, shade the pond 
  • above 100 F (38°C) - temperature is NOT suitable for ranchu

Historically, there would be a white tile placed on the bottom of a ranchu pond. The ranchu master would then decide on the water change, based on how bright or muted the white tile would get.

Effect of Green Water Changes On Ranchu Appearance

100% water change increases ranchu activity and appetite. With frequent 100% water changes, fish will actively grow in length and the head-growth development will be slower. Also, the scale development may not keep up with the rate of growth, resulting in irregular scaling and color disadvantages. 

If the infrequency of 100% water changes is decreased, the fish will be less active and have less appetite, as the water "ages". Ranchu will grow less in length, encouraging development of the head-growth. It will also help to set finer scales.

Warning: Keeping ranchu in old water for too long may stunt the young ranchu and result in sickness.

When water changes increase:
  • fish is active, increased appetite 
  • fish grows in length 
  • head-growth is poor 
  • uneven scales development can occur 
  • tail may fold 

When water changes decrease:
  • fish activity is reduced and appetite decreased 
  • growth in length is suppressed 
  • head-growth develops 
  • scales are finely set 
  • due to less movement, tail will not fold 

This is also applies, when no green water method is used. Whether green water is used or not, balancing the time that ranchu spend in fresh and old water will affect the fish appearance. This alone, might be one of the most important conditions in raising traditional Japanese top view ranchu!

Sunday, August 27, 2017


read introduction here

Tap Water

Tap or municipal water has pretty stable quality and good amount of oxygen. However, it needs to be treated for chlorine and/or chloramine. If left untreated, it is deadly for the fish. Please read here about the water conditioners. Depending on the region, tap water can be too soft and needs to be buffered and pH adjusted.

Well Water

In general, well water is not suitable for ranchu as it pumped out straight from the ground. It is often depleted of oxygen and can be too hard. A lab test can be performed to determine water composition. As a benefit, however, well water contains minerals and calcium that aids in skeletal development. It was observed that tail tension develops well in hard water, but it will slow down general growth of the fish, as compared with softer water. 

If using well water, for the best results, it can be mixed with tap water and aerated for at least overnight. In some set ups, water that is pumped out of the ground goes through the aerator tank. In this case it contains some oxygen and can be used for ranchu right away, considering that there are airstones in the ranchu pond. Read more here.

River or Lake Water

This water is not recommended for keeping ranchu. It may contain pathogens and parasites that can harm ranchu.

Green Algae Growth On The Surfaces Of The Pond

Green algae is a great food source for foraging ranchu. It is also where plankton lives. When green algae cover walls and bottom of the pond, they create a darker background to which fish reacts by developing a darker and richer color as a camouflage. It is believed that green algae growth is almost equally effective as use of green water. Benefits of green algae growth:

  • a place where plankton develops 
  • as a food rich in protein, vitamins and minerals 
  • pro-kinetic effect increases gastrointestinal activity 
  • positive for overall physical condition 
  • effecting fish color and its darkness 
  • promotes development of muscle tissue 

Cleaning the Pond

Algae growth on walls and bottom of the pond is beneficial to ranchu. Do not strip it all at once. Alternate cleaning of walls with cleaning of bottom to keep some of the algae growing at all times.

Clean the pond by brushing the walls and the bottom when algae growth gets too thick. Rinse the pond between cleanings. Read more here about the algae growth.

Friday, August 25, 2017


Some years ago, when I searched the Internet with a fine tooth comb looking for everything and anything that had to do with Japanese Top View Ranchu, I stumbled upon a website with chapters from Master Ito Takashi's publication on raising ranchu. All written in Japanese, the chapters addressed various subjects of raising ranchu from eggs to adults. 

Fearlessly, with no knowledge of the Japanese language, I embarked on the task of "translating" the chapters using the modern day technology. First, I let Google translate the text into what I called "JapaGooglEnglish". Then, I began to interpret the text based on my best knowledge of ranchu. I also ran some stubborn texts through different online translators to get a better understanding.

In the end, most of the "translation" made sense, at least to me, and greatly advanced me in performing my ranchu husbandry. With careful consideration, I decided to share this information, hoping that others might find it useful as well. Although, I give credit to Master Ito Takashi, please accept these series of posts only as an adaption of his publication. While reading, apply your own judgment. After all, raising ranchu isn't all written in stone and we should derive our pleasure from this hobby by making it very personal and even intimate.

Links to published chapters are below. I will be adding new chapters from the list regularly:




Thursday, August 17, 2017


I have stumbled upon a very interesting paper published in Zygote, Volume 20, Issue 1, February, 2012, pp.79-85, Cambridge University Press.

Attempt at cloning high-quality goldfish breed ‘Ranchu’ by fin-cultured cell nuclear transplantation

Daisuke Tanaka, Akito Takahashi, Akinori Takai, Hiromi Ohta and Koichi Ueno


The viability of ornamental fish culture relies on the maintenance of high-quality breeds. To improve the profitability of culture operations we attempted to produce cloned fish from the somatic nucleus of the high-quality Japanese goldfish (Carassius auratus auratus) breed ‘Ranchu’. We transplanted the nucleus of a cultured fin-cell from an adult Ranchu into the non-enucleated egg of the original goldfish breed ‘Wakin’. Of the 2323 eggs we treated, 802 underwent cleavage, 321 reached the blastula stage, and 51 reached the gastrula stage. Two of the gastrulas developed until the hatching stage. A considerable number of nuclear transplants retained only the donor nucleus. Some of these had only a 2n nucleus derived from the same donor fish. Our results provide insights into the process of somatic cell nuclear transplantation in teleosts, and the cloning of Ranchu.


Cleavage - is the division of cells in the early embryo.
Blastula stage - is a hollow sphere of cells, referred to as blastomeres, surrounding an inner fluid-filled cavity called the blastocoele formed during an early stage of embryonic development in animals.
Gastrula stage - early stage during which the single-layered blastula is reorganized into a multilayered structure.
Teleost - a large group comprising all ray-finned fishes.

2017 © Alexander Vasiljev

Friday, July 21, 2017


Here is my last ranchu from the same spawn of April 15, 2014. This male OYA is a very nice looking fish with bright red color and neat, well arranged scales. This ranchu is very similar to the ranchu I described in part II, in terms of scaling, coloration, body shape and tail.

Little over 3 months old. Photographed on July 28, 2014

Little over 5 months old. Photographed on September 27, 2014

Little under 10 months old. Photographed on February 6, 2015

Little under 1 years and 7 months old. Photographed on November 2, 2015

Little under 3 years and 3 months old. Photographed on July 5, 2017


Currently, this male Oya ranchu is close to 6 in (15 cm) long. As you can see, nothing much changed in his body and tail shape, other than him getting bigger. The head has formed into Shishigashira type, which is somewhat vintage for a modern ranchu. His tail, however, ended up with more red markings.


As NISAI fish transitions to OYA, it is harder and harder to keep them in shape. While the tail may not have any dramatic changes with age, the body and head do. My goal is to raise "lean" TVR. I prefer the body outline, as viewed from above, to be more elongated, with no protruding belly, so that the sides from head to beginning of O-Tsutsu (tail peduncle) are somewhat parallel. I also like it if the head width stays not much wider than the width of the back, a cigar shape. 

From the side, I like Se-Koshi (back curvature) to be as flat as possible up to the start of O-Tsutsu (tail peduncle). Reminiscent of a long Japanese boxwood comb. For body parts terminology please click here.

Quality of food and its portioning, along with exercise, is crucial to keeping ranchu in good shape. I will write about this subject in a separate article, reflecting on my experience.

Sunday, July 16, 2017


Presenting my next OYA fish - a female from the same spawn of April 15, 2014. She has always been a strong fish. Body shape is a bit shorter than in previously discussed RANCHU, but still proportionate.

Little over 2 months old. Photographed on June 5, 2014

Little under 3 months old. Photographed on July 8, 2014

Little over 3 months old. Photographed on July 28, 2014

Little over 5 months old. Photographed on September 27, 2014

Little under 1 years and 7 months old. Photographed on November 2, 2015

Little under 3 years and 3 months old. Photographed on July 5, 2017


Today it is a strong and active female OYA fish of 6.5 in (16.5 cm) long. The body remains a bit short for my liking, but the overall shape is good. O-TSUKE (tail peduncle scale bracelet) and O-ZARA (under-tail plate) were and remain very good. The tail's O-GATA (tail shoulders) used to be quite stiff, but became somewhat more elastic with age - an improvement.

As seen in photos, this fish has started to loose her red markings pretty early, as she was still developing. Now there is only one red eye with no more red left.

For body parts terminology please click here.

Monday, July 10, 2017


Presenting my next ranchu - male fish study from TOSAY to current OYA, hatched on April 14, 2014. I really like this fish. Since it was CBR it displayed very neat scales - small, consistent and well placed.

Little over 3 months old. Photographed on July 28, 2014

Little over 5 months old. Photographed on September 27, 2014

Little under 1 year and 7 months old. Photographed on November 2, 2015

Little under 3 years and 3 months old. Photographed on July 5, 2017


Currently a beautiful OYA fish of 6 in (15.25 cm) long. The body isn't changing much throughout the years. Elongated shape and overall outline is what I was trying to feature in this ranchu. The tail has no visible change as well, and maintained is coloration. The head, on the other hand, is changing. Its definitely widened but still slightly underdeveloped. The body color pattern somewhat changed. Body has lost a few "Azuki Bean" scales on either side. The head color pattern changed as well, from Ichimonji-aka or Red Straight Line to Kuchibeni or Lipstick, red outlined mouth.

Please feel free to post your own comments.

Wednesday, July 5, 2017


It was hard for me to find photos of ranchu development timeline to see how a particular ranchu changes over time. So, I have decided to periodically photograph four of my fish, which hatched on April 14, 2014.

It is a great way to study and see the grooming faults and successes through the years. It is also a way to observe aging tendencies in a particular bloodline if you are concerned with how your ranchu will look in late OYA age.

So here is the female fish study from CBR to current OYA, since 2014.

Little under 3 months old. Photographed on July 8, 2014

Little over 3 months old. Photographed on July 28, 2014

Little over 5 months old. Photographed on September 27, 2014

Little under 10 months old. Photographed on February 6, 2015

Little under 1 years and 7 months old. Photographed on November 2, 2015

Little under 3 years and 3 months old. Photographed on July 5, 2017


For me, this is a remarkable OYA fish of 6 in (15.25 cm) long. The body didn't change much and retained its elongated shape and good outline. The tail has no visible changes and maintains a good outline and placement. The head, on the other hand, is changing. Its become wider, but kept its overall shape without an overgrown wen. Also, the coloration and pattern are stable, with very minimal changes.

Please feel free to post your own comments.

Monday, January 2, 2017


As the year just turned, a group of my OYA ranchu are nearing four-years-old of age. It is an exciting time for me, to observe these fish since they have hatched in April of 2014. This group have not lost their beauty, their scales are tight, their colors are vibrant, their body and tail shape is holding well; the swim is graceful.

Please enjoy this video of my ranchu as I see them today.