Black Molly at bottom of tank
Last week we introduced 2 Molly fish and 4 guppies to our aquarium. We already had 4 neon tetras and 4 black tip tetras and have had the tank for 5 months and do a water cycle once a week.
We did a water cycle two days ago and all the other fish are okay apart from our black molly who is just sitting at the bottom of the tank hardly swimming/ moving. It tried to come up for food but look liked it was struggling to swim as if she was too heavy. Could it be pregnant or something else wrong? What should we do?
We have tested the ammonia and nitrate level and both came back okay.
Any advice would be hugely apprecaited.