I have two cory catfish. They seem very healthy and they swim together all the time. But one of them has this white thing on his back behind his dorsal fin. Sort of looks like a worm but I don't think it is a worm. Any ideas?
I would add something around 1tbsp salt/10g and see if that helps. If not, something with formalin (like QuikCure) should do the trick; just be sure to follow manufactorers instructions. I would also Q-tank him during treatment if you can.
I have just returned to the aquarium hobby and have fallen in love with corys. I'm not sure about the white thing on your fish but I would strongly caution against using salt. Everything I have been reading has said that corys do not tolerate salt very well at all. I would suggest looking at some other sites and forums before adding salt to a cory tank. A good site I've found is corydorasworld.com. Hope this helps and good luck with your fish.
I use salt all the time in tanks with cories..and more sensitive species like kuhli loaches and otos..at much higher concentrations than I am recommended. There was not even the slightest behavior change in any of my fihs. IMHO, IME, short term, it itsn't going to harm them.