Hello to all - I have a 330litre aquarium that has now been established for around 11 months. I have a community set up with few neon tetra, lemon tetra, black phantom tetra, silver hatchetfish, khuli loach, cory panda and some harlequims.

Over the past one month i have noticed some problems with the fish.Two of my black phanton tetra developed a sort of dark growth at the base of the tail. It is dark in colour, nothing like any white fungus patch.....it did not seem to bother the fish and I studied their behaviuor and it seemed fine. However over the past four days one of them now has a similar growth at the base of the pelvic fins and is now swimming with a small degree of difficulty. In addition one of the hatchetfish also has a similar protruding growth on the base of the pectoral fin.

I tried to research what this could possibly be but to no avail since I cannot find anything that seems to match these sysmptons.

I check the water parameters (nitrate ; ph) regularly and never had any problem. I effect water changes regualrly every two weeks.

The only 'different' thing that happened in the aquarium over the past month or so is that i had a small problem with blue/green algea. I increased water changes, dosed more oxygen and reduced light plus i cleaned manually a lot of the infected patches. All this seems to be working and the problem is now much under control.

Any help would be appreciated. Will try to attach some pics though quality is quite poor. Later this week will transfer the phantons to the hospital tank but would like to have an indication as to what the problem could be.