I just lost my blue-green chromis, and I'm trying to figure out what went wrong. He was fine until last night, eating and swimming normally in my 40-gallon tank with a dwarf fuzzy lionfish, marine betta, snowflake eel, and a new Singapore Angelfish I added yesterday. Before adding the Angel, I did a 10% water change. When I got home, I noticed he had turned white and was lying on the ground. After a bit, he turned back to normal color, but stayed on the sandbed. This kept happening - he'd turn white when the lights were off, then back to normal when they were on. This morning, he seemed weak and was laying sideways, getting up to swim, then laying down again. I left the house for a bit, and when I came back, he was under a ledge of live rock, breathing rapidly. I started researching diseases online, and he started swimming again, but would occasionally flip like he'd lost control. Then, he had some kind of seizure and eventually died.
My water parameters are: nitrates and nitrites at 0, pH at 8.4, and SG at 1.025. I'm planning to do another water change today to lower the SG.
I'm not sure what happened - could it have been Velvet? Or was the tank overcrowded? Is the SG too high? Maybe the dwarf lion stung him? Or was it the water change and new fish on the same day?
A mysterious death in the aquarium
Re: A mysterious death in the aquarium
Considering your salinity is a bit high, I have to wonder - when did you last calibrate your hydrometer against a reference solution to ensure its accuracy?