I'm looking for theories on why most fish don't survive long in one of my tanks.
100 gallon, slightly overstocked maybe, but then so are my smaller tanks.
Under 50 small fish.
Tank started 6 years ago.
Problem started after only a couple months.
I have 5 long term survivors, 5 plus years.
Glass bloodfin, rummy, celestial danio, panda garra, hillstream loach.
fish die with various symptoms, some have cataracts, some do spinning, fast breathing, dropsy, swim bladder, tumors, red streaks, and overnight deaths, etc.
I currently have 3 male furcata rainbows with swim bladder and scoliosis issues.
Females from different store look good so far.
Lost a 2 year old killi last month got very slight looking whitish upper tip sinus area and then fast breathing, refused food.
kanaplex didn't help.
I do weekly 50% water changes.
use 25 watt UV a few hours a day, heats the tank too much to keep on.
2 canister filters, monthly cleaning, but only removed the hoses to clean twice.
Gravel vac every other week.
many somewhat healthy plants, no CO2 discontinued a few years ago too many fish deaths.
neutral soft water from tap.
I've in the past tried various antibiotics to try to kill possible bacteria.
Taken out a lot of gravel so not as deep as I originally had it.
Good water flow, don't think there are any dead spots, removed all wood and rocks.
I wanted an aquascape, now a very plain tank just trying to keep fish alive.