last week, we observed several "parasites/leech" on freshly laid zebrafish eggs. Please see the video and photo attached. Has someone seen such organism ? Can someone identify it ? and eventually knows how to get rid of it?
thanks for your help.
Why do you think they are parasites? Did you notice any reduced survival? I would not worry about that and they may be part of the normal ecosystem of the fish facility which is not sterile but includes a number f small invertebrates in the biofilm and biofilter.
Yes, we have seen them before, I don't think they are doing damage to the fish. They appear more frequently if there are bad eggs, and they grow more rapidly when having a higher density of eggs in the dishes. If regular health checks for parasites in the fish are up to date with your fish facility, and you have not noticed a reduction in survival rate, keeping less fish in one dish and removing bad eggs at an early stage should help, and keep an eye on water quality of course. It could be introduced through food in the fish facility. Nothing too big to be worried about.
Your video looks like a bdelloid rotifer to me.
https://en.wikipedia.org/wiki/Bdelloidea
They filer feed on suspended matter in the water. There would be more food for them in dirty water conditions and when dead eggs are rotting.
In my view, unlikely to be parasites.
Other kinds of rotifers can be used as food for fish larvae.
Good cleaning of the collected eggs and perhaps light bleaching of the eggs (which some do all the time) will eliminate than and the things they feed on.
However, there are other little things in the water that can attack your eggs, like Coleps.
https://en.wikipedia.org/wiki/Coleps
They can occur in very large numbers and attack and eat fish eggs.
Treat as recommended for bdelloid rotifers.
Its good to figure out and understand what you have in the water, in order to deal with these problems.
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