Originally Posted by snarkbandersnatch
I have a 35 litre tank (and I am aware that I probably had too many fish to start with and this might be the cause of all my ills).
Dwelling within it until recently were two chocolate orandas, two zebra danio, two loaches and an apple snail.
All has been well for eight months until the apple snail died. Did a water check and carried out a clean as directed and all was normal.
A month later, we went away for a week with a neighbour feeding the fish on our behalf, switching the tank lights on and off etc etc during which time one of the orandas died (troublingly, neighbour did not notice and the loaches polished off most of the remains).
This oranda had showed signs of cotton-wool growths a fortnight earlier but I treated this and the problem seemed to be resolved.
I got back, carried out a clean and everything was fine for three weeks. We had a local fish centre carry out a water check and all the relevant levels tested fine.
On Thursday, we left for three days with none of the remaining fish showing any signs of distress. Instead of relying on a neighbour, we put one of those three-day pyramid feeders in the tank. I left the tank on its blue light setting.
Second oranda died - again discovered partially devoured.
Danios and loaches showing no signs of distress or illness.
Any guidance as to what I may be doing wrong will be appreciated!!
You are attempting to keep numbers of fish better suited to much larger tank.
As fish grow, we feed them more ,and they produce more waste.
Excess waste and or food leads to water quality issues especially in smaller tanks.
Fish gradually become weaker and weaker as water quality deteriorates and over time ,they become sick .
Without weekly ,or twice weekly water changes, the fish are swimming in their own poop.
Some fish show the effects of poor water conditions before others.
Gold fish being the larger fish and requiring more oxygen rich clean water, look to have been the first to succumb in this case.
Best to provide the fish with larger tank that has better dilution capabilities between regular weekly water changes than smaller tanks.
When leaving for a few days,best to feed the fish before you leave (regular amount) and then if you are not going to be away for much more than a week,, let the fshes go without. Healthy fishes can go up to a week without food with no harm.
Or for the goldfish,, you could place some live floating plants in the tank that they can nibble on while you are away.