cognizant

Let me first mention that I do not need to do this now, but would like to be prepared in the future. (Hopefully the very distant future)

When a fish passes away (like a betta) and you want to add a new one to the tank, what is the best way to clean the tank out? Should all the gravel and items be removed and replaced? Is there a way to clean them off and put them back in? Are you supposed to clean the filter and change the cartridge? Or can you keep the old ones? What else would need to be done before restocking the tank?

clinton1621

It depends on the cause of death... only contagious diseases would require a full tank sterilization, any other causes of death and you wouldnt have to really do anything (other than remove the dead fish obviously)

Allie

You could take the decorations out to dry creepy tank things will die by air. BUT make sure to rinse them under tap water first the chlorine will kill parasites or bacteria. I have boiled them before but forgot my silk plants have plastic stems...my plants are a tad crazy looking now, lol. Boil only things that can be boiled.
What I did after my C.worms adventure, was put a cap full of bleach in the tank with everything in it. Let it sit over night then do a 50% water change...wait another few days if you still smell bleach (not usually), do another 25% water change.
This means you have to start the cycle all over again so I wouldn't do the bleach thing unless you have something really contagious happening.
I wouldn't add the new fish for at least 2 weeks after a death. If it's a parasite that needs a fish to live...it would eventually die off from not having a food source.