A WAY TO RAISE RANCHU ● CULLING ROUND - I

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.


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Links to published chapters:

● INTRODUCTION
● WATER
● NOTES ON GREEN WATER & WATER CHANGE
● WATER TEMPERATURE
● AERATION
● SUNLIGHT AND SHADE
● CONTAINERS FOR RAISING RANCHU
● FOOD
● FEEDING REGIMENT
● BREEDING & SPAWNING
● RAISING & GROOMING FRY
● GROOMING KUROKO AND TOSAI
● CULLING
● SELECTION METHODS
● CULLING ROUND - I
● CULLING ROUND - II
● CULLING ROUND - III
● CULLING ROUND - IV
● CULLING ROUND - V
● FORSEEING RANCHU CHANGES IN THE FUTURE

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A WAY TO RAISE RANCHU ● GROOMING KUROKO AND TOSAI

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.

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Links to published chapters:

● INTRODUCTION
● WATER
● NOTES ON GREEN WATER & WATER CHANGE
● WATER TEMPERATURE
● AERATION
● SUNLIGHT AND SHADE
● CONTAINERS FOR RAISING RANCHU
● FOOD
● FEEDING REGIMENT
● BREEDING & SPAWNING
● RAISING & GROOMING FRY
● GROOMING KUROKO AND TOSAI
● CULLING
● SELECTION METHODS
● CULLING ROUND - I
● CULLING ROUND - II
● CULLING ROUND - III
● CULLING ROUND - IV
● CULLING ROUND - V
● FORSEEING RANCHU CHANGES IN THE FUTURE

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