Hi I have 3 (was 4 until last week) zebra danios in an Aquael Leddy 60 tank. Following a water change a few weeks ago I noticed one of my danios acting strangely. It eventually developed what i now think was some kind of fungal infection and died.
2 more of my danios are now acting strangely - permanently staying at the bottom of the tank in the flow from the filter and not eating. One of them looks like it's got a bit of its mouth missing - see attached picture - I'm sure it wasn't like this before.
Does anyone have any advice on what may be wrong - either by behaviour or the picture?
The tank is still cycling (I researched and stupidly thought that fish-in cycling would be ok as I was daunted by a how to do a fishless cycle - how I regret that decision), however I monitor water levels closely using the API Freshwater Master Test Kit. I've had the fish since the 24th April and ammonia levels are normally less than 0.25 and nitrite/nitrates 0 when I test, apart from a period in May when ammonia went up to 0.50 and nitrite 0.75 (I was going on holiday for a week so I then performed a big water change and added some Tetra Safestart - since then I've had low ammonia and not yet any nitrites).
Thank you for the reply. Unfortunately we're going on holiday tomorrow, terrible timing, and I can't get Esha 2000 locally so I've bought a fmfungus treatment for mouth and fin rot from pets at home. They seem to have perked up a bit, although that could be wishful thinking.