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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