Hope I have covered all the points here - used a different template. I can redo if necessary.
I am at a complete loss. No idea what is killing off my long established colony.
1. Water parameters
a) Temperature range. - 25 C
b) pH. 7.3
c) GH. 12
d) KH 6
e)Ammonia 0 , Nitrate 40 , Nitrite 0
f) Water change frequency
twice weekly 10-15% each time
2. Tank set up
a) Size. 2700 litres
b) Substrate. sand
c) Filtration. 4 fx5
d) Furnishings. bogwood, ornaments
e) Other tank mates. filament barbs, clown loaches, synodontis, scissortails, L066, L340 , clown plecs, banjo cat, midnight cats, cories, porthole cats, rainbow cichlids
f) How long has it been set-up? At least a year, probably 2 years
g) When was the last new fish added? 3 months L66
h) Foods used and frequency? twice daily, flake am, catfish pellets, courgette, frozen bloodworm, live river shrimp - harvested from other tank.
3. Symptoms / Problem description
No symptoms until they turn up dead but after losing a couple of 8 years plus bn females I have now lost more of them and am now losing males. Lost both of my alpha males.
Younger fish seem fine. I have had several bloodlines in there over the years.
No other fish are affected.
No changes to the tank at all.
I have new fish in other tanks but so far as I know I have not cross contaminated and bn seem fine.
4. Action taken (if any)
Tested water as above.
Large water changes - hma water. Taken out some of the furniture so bodies more easily found.
5. Medications used (if any)
Ideas anyone ? Inbreeding issues. Can't see how anything would be so specific to particular fish. Lost my second alpha male yesterday - he had the best branching bristles, really complex - just like a mature stag.