Omnipresent Parasites & parasite free tosai

[gregbickal]

I wanted to bring this discussion over from the other board to get a larger audience, and hopefully some answers.

Here's a Hypothetical situation to ponder: If spawn parent koi (with flukes) in a pond, and immediately after spawning remove the parent koi, will the flukes live in the pond long enough to infect the eggs or the fry that hatch? Would this batch of fry be parasite free?

What parasites would live in this situation? Costia? Tricodina?

What parasites can live if the eggs were spawned on spawning ropes and only those were transferred to the hatching pond?

[Brutuscz]

Well, costia would live for sure. It is even known to resist drying and now salt. Persistent little buggers.

[MikeM]

Greg, I do not have the direct knowledge to answer your question; but I do believe the greatest threats to any fish fry are (1) the presence of parasites and (2)absence of appropriately minute food. They are too delicate to endure an infestation or lack of nutrition. Most parasites throw young/eggs into the water environment. I think it always the better practice not to breed fish known to have parasites and to avoid spawning quarters with parasites. In regard to koi, I think the leading Japanese breeders follow rather sterile processes in spawning, but I'll leave to others with more direct current knowledge to comment further.