ill fish

I’ve had some black widow tetra in my 90l tank for quite a while now 3-4+ months and they’ve been quite fine however today I noticed one of them with what looks to be quite bloated and has to keep using his fins to keep himself from dropping to the bottom of the tank. I’ve struggled to get good...

I have a 20g tank just her and LG pleco, had her for about 2 yed. What are the dark spots appearing and what about the fraying of her tail find? I've only just noticed the spots the last couple of days. Seems to be eating decent, and acts a bit lethargic. What could this be?

I have an aquarium (around 30 gallons) it's heavily planted. It Has 65% water changes weekly. I've kept 3 bumblee gobys in there for a few months with no issues. I also had 2 figure 8's which id kept with them for a few months with no issues. I purchased a third puffer. 2 weeks later the 3...