Fry Mortality

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pelleeklund

pelleeklund

Peacock Bass
MFK Member
May 23, 2009
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Pennsylvania
I was curious whether it is normal for a batch of fry to slowly die off as they grow. I have mine alone in a 30 gallon with no gravel with a sponge filter running. It seems like the best and biggest of the bunch are doing well and looking great while the runts are dropping. Seems natural enough to me but I'd like to make sure. They are Jag/Cons so I have been assuming the larger ones are snapping on the smaller ones to monopolize the food/space in the tank. They are fed twice a day with crushed brine shrimp and crushed flake food. The filter may be more powerful than necessary, although the healthy fry have no problem with the current or suction. I don't keep test kits so I can't give water perimeters but I keep the 30 as I do my 220 and 55 which never lose fish. I will test it if I find out that the fry dying off is abnormal. The remaining fry are about 1.5 to 2 months old and are about a quarter inch in length. Thanks for any help.
 
Yes it is. I had about 100 fry couple months ago, now i have 16
 
they do say 1 in 50 survive in the wild, i'm sure that's because they become part of the food chain, but also they are highly susceptible to bacteria at early stages. I've read other breeders threads and this is totally normal.
 
I disagree, in a tank raised environment you can raise high percentages, then cull runts and deformities. Someone's the aggressive ones aren't necessarily the nicer quality ones, need to give them all a change. My 3 cents:

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I currently have three sets of fry (Convicts, Fantail Goldfish, and Jack Demsey's). Even with perfect tank conditions...in my experience...you will almost always end up with far fewer fry/small fish than you started with. Simply for one reason...competition. Fish (like all animals) are very competitive.

Some will be more aggressive getting to the food, some will eat more than their fair share of the food (even if you overfeed)...and those that get more food will get larger faster...and then these guys will start to eat the very small weak ones as in-between meal snacks!;) Then add on loss's due to imperfect conditions...and the result is...if you end up with 20-25% of what you started with...you're doing pretty good.

Then...if you cull for quality...you are certainly going to have far less than that 20-25%.
 
pelleeklund said:
I was curious whether it is normal for a batch of fry to slowly die off as they grow. I have mine alone in a 30 gallon with no gravel with a sponge filter running. It seems like the best and biggest of the bunch are doing well and looking great while the runts are dropping. Seems natural enough to me but I'd like to make sure. They are Jag/Cons so I have been assuming the larger ones are snapping on the smaller ones to monopolize the food/space in the tank. They are fed twice a day with crushed brine shrimp and crushed flake food. The filter may be more powerful than necessary, although the healthy fry have no problem with the current or suction. I don't keep test kits so I can't give water perimeters but I keep the 30 as I do my 220 and 55 which never lose fish. I will test it if I find out that the fry dying off is abnormal. The remaining fry are about 1.5 to 2 months old and are about a quarter inch in length. Thanks for any help.
Click to expand...

do 50% water changes for the first two weeks.......bbs is the best way......
 
I think space, food, and water quality are the main requirements to raising frys. I used to breed fishes and you can raise most of them up to marketable size. "Most" meaning 90 percent. Good Luck.
 
Thanks everybody. Good to know that it is more common than not that the batch thins over time. I'm not really interested in upping my percentages either, due to the fact that I only plan on growing one or two out, the rest would have become feeders anyway. I'm just going to proceed naturally and see who makes the cut in the end. I appreciate the replies.
 
would the mortality rate much be higher if you separate all the fry apart from their parents? just askin.
 
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