The brown algae is harmless diamtoeous algae.
You need to put a filter in there to process ammonia and nitrite.
If you cannot give the fish water free of ammonia and nitrite they will die.
Get one of those air powered sponge filters, the round black ones with a
weighted base.
Once cycled they are good bio.
If it really is a the fish eating fins, feed them more.
but odds are espec with the 'new tank syndrome' algae blooms and
deaths/behaviour.
You are keeping it too clean.
Grow some filter bacteria!!!!




"fhapgood" wrote in message
oups.com...
Let me add some more history, just to see if it sparks a response.

Like I say, I kept these two GF, both on the order of 7-8" in a 50
gallon tank. I swap out 5 gallons a day, every day. My filter isn't
much, but I figure
given I am adding clean water at a pretty fair rate I don't need the
best in the crowd.

About a year out of nowhere I started getting some kind of growth in
the tank. It's like a brown algae, which I guess means it might be a
fungus, though in fact I think I have read that there are brown algae
-- they carry enough brown pigment to overpower the chlorophyll.
That's what it looks like, but it doesn't seem like the fish are
eating it. After a year or so one of the big fish died. Perhaps there
was a connection -- I think the GF fish were about ten years old,
which might be getting on for a GF or it might be the first blush oif
adolescence, I dunno. After the first fish died I noticed that the
second started to look "old" -- slow and lethargic and quiet. It sits
on the bottom of the tank a lot doing nothing, which it didn't use to
do. Perhaps it is getting old or perhaps the brown algae killed the
first fish and is now burdening the survivor. On the other hand the
feeder fish I just got, the fin eater, could
not have been livelier.

Any of this ring a bell with anyone??