Any fish keeping enthusiasts - help me with identifying a pest, please...?

Question

We have 5 Blackmoor fish in our aquarium. This morning I found on one of them a flat yellowish transparent creature, that's stuck on one of them - it was on their tummy now it's near the eye, it seems to have some legs or feelers, it's only about half a centimetre long, so I can't give a better description.. Does anybody know what it is, if it's harmful to my fish (it certainly doesn't look pleasant) and what to do with it?
Any info greatly appreciated, guys, thank you.

Answer 1

That would either be a fish louse as Venice Girl describes or trematodes. There are literally 1000's of types of trematodes and hundreds that fit the general description you give. Most will respond to the treatment above for Fish Lice, some will not. Many will also respond well to a salt treatment as low as 1%, but slightly higher is better as it would kill even more species. I would suggest you follow the treatment above but also add 2 tablespoons of salt per 5 gallons of tank water. If this doesn't remove all of them within 3 days I would suggest you treat with copper. Copper will kill any parasites in the tank , but is also quite stressful for the fish and should among the last resort medications. Copper is often sold as snail killer in aquarium stores, you can treat as the bottle suggests but that is a minimally effective dose. If you would like to use copper I would be glad to help you calculate the needed dose. I would need you to send me your tank size, temperature, pH and preferablyKh (Carbonate hardness). If you don't have test kits for all of those, call around and find a pet shop that will do the testing.

Oh, poor water does not cause parasites, they got in your tank somehow, but not because of poor water. Poor water causing diseases is a rule that applies to very, very, very few diseases. The majority are caused by other things.

Best of luck with it

MM

Answer 2

Because you say this is moving around on the fish, it could be fish lice. It's very common and easily visible and will leave tiny red spots where it was previously attached. Lice is a very dangerous parasite. The open wounds are susceptible to secondary infections. Additionally, the lice will lay eggs all over the aquarium and after only a few days, will be out on the hunt again for fish to attach to. This whole process takes 30-100 days depending on the temperature of the water. The best treatment is with medication containing Diflubenzuron, like Anchors Away (treat as directed on the package) or Dimillin (3 times with 6 days apart). Additionally, remove the fish from the tank, lay it down on a towel and, while holding it down with another towel to minimize flipping and damage to the skin, the visible fish lice should be taken off of the fishes body with tweezers and treat the red spot that the hooks leave behind with neosporin or Panalog. Virtually all diseases can be attributed to poor water quality, whether from your tank directly or from a previous tank where you bought your fish. The first thought is this. For five goldfish, you need a minimum of a 50 gallon tank, and I'm gonna bet you don't have that. If you do, I apologize and that's great. If not, you need to get at the very least a 50 gallon tank ASAP or your fish are going to die due to overcrowding and poor water quality. Healthy fish are happy fish! Good luck!

Answer 3

perhaps it is some sort of copepod. Sorry can't offer more besides this.