Recently my fish have been dying in my 55 gal planted tank. At the
same time, one of my full grown angels has pretty much quit eating.
That and other angels seemed to have the stringy/white colored poop
that I understood was indicative of parasites.

Originally, I treated for external parisites, due to something
attached to the angel. Treated with Jungle Anchors Away
(diflubenzuron). When I determined what the things attached to the
angel were, and after they disappeared without improvement in the
angel, I treated with Paragon II (Metronidazole, Furazolidone). No
improvements.

Recently I have noticed 1 rosy barb gone, about 6-8 3-inch SAEs (I
have had for several months) and two of three juveline golden angels
that I had raised from the spawn of my gold angel pair.

I have had in the tank: two adult angels, 6 small angels, 2 rosy
barbs, 12 SAEs, 4-5 otos, 2 catfish, 1 clown loach, two other loaches.

Only fish change in last few months was to add 3 gold angels I had
raised from my spawning pair.

Only plant change in last few months were 3 plants (2 of the crypts)
that I bought in Houston at the conclusion of the AGA conference.

My otocinculus seem to be fine.

Seem to have about 2 SAEs left.

Haven't seen the loaches recently, but that is not unusual.

The tank has been quite stable for months. Got the SAEs in early
Summer. Lost one nice angel a few months back. Never sure what
happened.

Today I tested the water. pH 6.6 Ammonia 0 Nitrite 0 Nitrate 0

I have injected Co2 and about 3 watts per gallon light. LIghts on
automatic about 11 hours a day.

My tank is heavily planted. I huge amazon sword takes up about 1/2 of
the 55 gal. @ smaller swords. Also have E. tenellis (not growning
well - just stagnant). Some small sag. that is doing well. Several
(6-8) crypts also doing GREAT. Wisteria, sunset hygro and bacopa that
grow "while you are looking at them". Also a red rubin sword and
several plants. I have to trim the hygro and bacopa weekly to allow
space for the fish to swim.

Tried trimming the large leaves of my large sword, as the leaves fold
over on the surface. 12-15 inches long and 3-4 inches wide. Today I
tried to trim out the same leaves.

I put several Seachem Flourish tabs in the gravel near the plants.

Recently I resumed dosing weekly with Seachem Flourish, per label.

Today I vacuumed the gravel (where I could get to it due to the
plants) and changed about 40% of the water. I switched to Amquel to
avoid other dechlorinators that remove trace heavy metals that the
plants need.

Suggestions?

Bob