Juvenille Clownfish disease...please help!

[cdipasquale]

Ok, I have been searching for hours and can find nothing like this. My baby clownfish are about 50 days old and I am slowly loosing them to something that I can't figure out. They are all getting something brown on their fins and sometimes it seems to be attached to the bottom of their gills, maybe coming out of the gills but they are too small to tell for certain. They are eating great and start getting this stuff on them and within a day or two they are on the bottom breathing heavy and then they die. It looks like the gunk that builds up on the bottom from feeding and poop is sticking to them, but it ends up killing them. I siphon the bottoms every day to keep at a minimum but there is no way to avoid this stuff completely. I have been using melafix, as a guess I thought it could be fin rot but i've never seen finrot before so i'm not really sure, but it doesn't seem to be helping at all and if this keeps up, I wont have any fish left in another week.
System parameters:
120 gallons, fish are in a 15 gallon compartment (about 40 fish).
Specific Gravity 1.023
Temp 80*
PH 8.3
Ammonia 0
Nitrite 0 was .25 last week because the system is fairly new.
Nitrate 20

Everything seems to be fine and there are 2 pairs of adults clowns on the same system that are just fine, it's only the babies. Here are some pics. They are really bad pics, but I just can't get clear ones. Hopefully they at least give an idea of what i'm looking at. Please, someone tell me you know what is happening and how I can fix it. I have no idea if this is a parasite or bacteria, or really just the gunk from the bottom sticking to them.


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[cdipasquale]

Nobody has any ideas?

 

[MarinaP]

This is very odd. Take one out, wrap in a wet paper towel and scrape that stuff off. See what comes out. If you can look at that under the microscope - even better.

Your other option is to set up 3 treatment tanks. Dose one with copper, another one with antibiotic and the third one with Formalin. Break the babies in three test groups, one group per tank.

With you next batch I highly recommend setting up a separate tank for the fry. If I understand correctly, your fry tank is connected to your main system now.