Questions About Cleaning Tank After Fish Death


I recently had 2 bettas die in a 5 gallon, filtered, cycled tank.

One I had for a couple years and I think he just died because of old age. He started losing color and gradually getting weaker until he could barely eat even though I gave him tiny pellets. Lost him a few weeks ago.

I did a water change but didn't do any other cleaning in the tank. It was cycled and I removed the dead betta promptly. Transferred another betta into that tank because he had been in a 10 gallon with a couple amano shrimp and had been bullying the amanos. He was always picking at the algae wafers I put in for the shrimp and trying to take their food. I had noticed his belly bulging some and thought he was overeating because of taking the shrimps' food. So I figured he needed a space of his own. I fasted him a couple days and the swelling was less but not totally gone. He was a big betta though, so I started giving him just 2 pellets a day. The swelling seemed to increase a little again, so I fasted him again and was going to give him the pea treatment but then he became lethargic and I noticed his scales starting to raise some. Dropsy? I researched treatment for that but he died the next day.

So, now I'd like to move my betta that's in a 2.5 gallon into the 5 gallon. I've read everything from "just do a water change" to "bleach everything, throw away all the media and gravel and plants and start over" before putting a new fish in a tank where one has died. I pulled out the filter media and just have it in tank water for now. I emptied the water from the tank. I was wondering if I pour some boiling water over the silk plants and gravel and rinse well would that be enough to make them safe to reuse? Do I need to discard the filter media and everything? I was thinking I can just transfer the filter in the 2.5 gallon along with the fish, unless I find another fishie to go in the 2.5 gallon. I can't resist looking at the bettas whenever I go to Petco. Some said use bleach and water but I also read that the bleach is hard to totally clean out and can harm fish.

So what cleaning methods have you used that have worked, if possible without throwing away stuff, and not ending up with your next fish dying?

maggie thecat

I generally just give the tank a good vacuum and water change and maybe freshen up (not completely replace ) the filter media. An empty tank is a good time to deep clean. (Although my tanks are never truly empty because I keep shrimp and snails.)

If you suspect a contagious pathogen then "nuke" the tank. Ditch all media, substrates, etc. Scrub, bleach and then neutralize the bleach in conditioned water any hardscape and the tank. Replace hoses. Air dry in the sun.

Start over establishing a new cycle

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