Backyard Aquaponics
A place to discuss aquaponics

I am purchasing Mike Sipe's parent breeders to generate "PennyFish" F1 hybrids. These were originally touted to produce 99% males. Now, apparently due to a line corruption, the male percentage is more like 80%.

A friend of mine suggested putting in a false mesh bottom in the fish tank, say an inch or few cms off the real bottom, to discourage breeding, as any eggs produced would drop through and be lost.

Has any one here tried this? If so, what materials were used and and how was it managed? Is it even likely to be worthwhile?

Thanks,

Jim

I'm not familiar with the fish or the size of them or their eggs. Some crayfish farmers pretty commonly use mesh bottoms for the fry to fall through to escape cannibalism so it ought to work. Vinyl coated hardware cloth should work fine. If trimmed, coat the ends with 100% pure silicone rubber, not Silicone II as it is toxic to fish. Coating the cut ends will seal it and keep the wire ends from rusting and possible metals leaching into the water from galvanized wire being exposed. Another option might be the vinyl diamond weave used to make gutter guards as it has no wire in it.

That's all I can think of. Not familiar either with the breeding methods of these fish. Will not the eggs be fertilized by male sperm being present in the water?

You could essentially use most any netting or plastic mesh cage material (that is of the right size to allow eggs and milt to fall through but keep the fish from picking the eggs back up for brooding. This is kinda part of cage culture so if you had the capital to set up your system with cages it could even make harvest/grading etc easier.

Mornings

Something on it here under fish species. While this is cage growing I do not see why it could not apply to a mesh bottomed tank.
http://www.thefishsite.com/articles/135 ... of-tilapia

Charlie,

Thanks for the suggestions. I think that will work very well.

Tilapia can do a full breeding cycle (egg to fingerling) within 10 to 14 days, every 10 to 14 days -- very prolific, and they grow very fast too. Down side is when the females produce young ones they don't grow. The other trade off, at least in temperate climes, is the water must be kept at around 85F, 30C.

If the eggs fall through the false bottom, the mother cannot hold them in her mouth to incubate them, fertile or no.

Jim

If the eggs are on the bottom, you'll have to pick'em up quick as they get mould very fast.
I've done it with other fish and it works all right as long as you take the eggs out and put them in a well oxygenated incubator.

I'm not sure that the fertilisation of the eggs will occur in this type of system because i suppose the male has to see the eggs on the bottom to fertilise them.
Best way to know is to try, keep us posted.

I think the intension with such a system is to not have breeding happening in the grow out tank. I don't think there is any desire to hatch such eggs.

A net box can be made, called a happa. They would help tilapia growers in two ways. One- prevent the hatching of eggs that fall through to the bottom. Two- make it easy to harvest the tilapia.

Of course the box can be made of other material beside mesh. Hardware cloth, wood etc.