What is this???

[Steve]

About a week ago I bought a doz "feeder fish" to stick in a open tank and grow out to put in my pond with some other fish I have in there. Luckily I quarantine all new fish now before adding them to anything because these suckers have something on them. I've lost all but 3 of the feeder fish in the past week and had no idea why. After looking over the dead one I pulled out today I found these.

They are about 1/8" and round in shape, greenish and clear, move on their own at a pretty decent rate, and obviously what are killing the fish. What the hell are are? some sort of fluke or worm or???

What should I treat them with too. I put a drop of Prazipro on one of the parasites that was on the dead fish and it seemed to kill it within a minute so I added a dose of Parzipro to the tank with the feeder fish in it. Should that do the trick on killing them or is there something else to use?

[Steve]

No one recognizes these...Am I breeding some sort of Newfangled creepy crawlies here? lol

[Regalblue]

No one recognizes these...Am I breeding some sort of Newfangled creepy crawlies here? lol

Nope,  No clue what's going on here.  Sorry bud

[Steve]

I think I may have found what it is. Been doing a lot of googling and found where Koi/Comet/Goldfish can commonly get what's called "Argulus" (feeder fish are goldfish/comets so this would pertain to them as well I think). It's a type of lice which is actually a tiny crustacean  that attaches to fish and sucks the blood out of them, and can swim freely on it's own. Sounds just like what these here are and the pics I found look VERY similar to the little creepies I took the pic of this morning.

If you google Argulus you'll see them. I'm pretty sure that's what this might be. Now to read up on how to rid them out of that holding tank.


Take a look at the 2nd pic, that's definitely  them http://www.fish-treatment.co.uk/freshwaterlice.html

[Ron]

Copper is poisonous to invertebrates (as are other heavy metals as well). Any parasite meds should knock them out, but if you happen to have spare pieces of copper piping (or another form of real copper, AKA not fake pennies) you can drop that in the tank as well and it should kill them off in time too.

I didn't read fully about the duration of their lifecycle, but I'd be cautious until all potential eggs are dead as well. Buying "feeder fish" is the most risky type of fish to buy IMO.