Art by Alexander Vasiljev, Copyright © 2017


Tuesday, April 3, 2018


read introduction here

First Culling Round - Two Weeks After Hatching

The fry size should be around 1/2 in (13 mm). The tail by now is clearly open and it is time to make first culling round. The selection is performed looking from above.

Main concern during this time is to look for the straight body line and open degree of tail shoulders, as well as open tail shape, as indicated in the picture below. Every other concern must be left for the next round.

The number of fish during the first round will be greatly reduces. First remove fish with obvious defects, then do more precise selection until the appropriate stocking density is reached. Once the needed stocking density reached you can only take out fish with obvious defects. Usually, the overall fry number should be reduced down to 10-15% after the first culling round is complete.

Negative Points To Look For (blue line shows defect):
  1. Wild carp tail regression, very easy to recognize
  2. The tail is not fully open; red line indicates desired angle of 160°-170° (ideally 180°), sometimes difficult to recognize, questionable cases can be left for round two 
  3. The tail in not open, left and right sides irregular 
  4. Twisted body or tail peduncle line (often happens when hatched in low water temperature) 
  5. Tail core forms a dark line continuing into the tail peduncle, if clearly visible 
  6. Tail split more then 1/2 of the center line length 
  7. No tail split. Although, not a fault 
  8. Asymmetrical tail shoulders 

Also look for:
  • fish that can’t swim straight
  • fish with poor growth rate
  • fish with any other obvious defects

During the First Round

Leave the fish with symmetrical tail, that is open no less then 160°-170° (ideally 180°, as in picture #2). Examine the tail tension. Keep in mind that tail tension has tendency to soften with time.

Thursday, February 1, 2018


read introduction here

The ability to recognize strengths and weaknesses in fast growing ranchu fry is very important. However, no matter how good the quality of a ranchu is, there will always be some fault.

It is wrong to look for all imperfections at once, when performing culling. The best is to seek out major drawbacks and leave off minor imperfections and not to overlook the fish's charm and overall appearance.

It takes years of experience and training to start recognizing of what is important and being able to balance between good traits and faults for achieving the iconic ranchu look.

Selecting Between the Good & the Poor Fish

During culling, skilled person will search for a good fish, while novice will often look for a bad fish. Partly, because it is easier to identify the bad fish first, especially when you have a little experience as what to look for. However, there are advantages and disadvantages in both methods.

Looking for a good fish:
  • culling must start early 
  • by selecting only good fish, the number is drastically reduced 
  • promising fish can be overlooked 
  • moderate to high experience is necessary 

Looking for a bad fish:
  • promising fish can not be overlooked  
  • time consuming 
  • hard to dramatically reduce the number of fish
  • suitable for a novice

Thursday, January 18, 2018


read introduction here

The Purpose of Culling

It is absolutely necessary to perform selection and culling to keep up and improve upon ranchu quality. In one spawn, ranchu can produce a lot of fish with undesirable characteristics. Strict selection of the fish with true ranchu qualities will assure that ranchu breed stays alive and continues its high quality traits.

During Ranchu Culling

Choose shady and well ventilated place during culling process. Sudden water temperature change will kill the fry. It is outmost important to keep the temperature as even as possible during selection and transfers of the fry from one container to another.

Choose large enough container size for culling and do not overstock. Overstocking and too small container will result in lack of oxygen. Also, water temperature in small container tends to fluctuate more freely in response to the air temperature.

To prevent water temperature change and lack of oxygen, floating box with netted bottom can be used to house the fry. The box floats in the pond, keeping the water parameters stable.

Culling Mistakes 

Often, a novice tends to keep most of the fish and performs selection and culling much later then required. The culling rounds must be performed on schedule. Overstocking may result in underdeveloped and lower quality fish.

During the early fry stages it is easier to identify many defects and major imperfections. That's why first culling round is performed drastically. The following rounds require more mastery and training, as one searches for the fish with superior qualities.

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