My sweet betta fish Flounder died today
I'm not sure what the cause of death was...at first I thought it was something to do with swimbladder; he was lethargic, wouldn't eat, and would either lay on the bottom of the tank or float near the top. But then he started rubbing against the rocks at the bottom of the tank, and I read that that could be an indicator of velvet or ich. He didn't have any spots on him or anything though. Tonight I noticed him struggling really hard to come up for air, and a few hours later he was dead. I'm heartbroken! I wasn't a fish person until I got Flounder, and now I love them, so he is very special to me.
That brings me to my question - I have another betta, Levi. He currently has his own tank but I really hate it and it's a strange shape that doesn't allow room for many decorations or anything. I really hate that tank. I wanted to move him to Flounder's old tank, but I don't know exactly what killed him, so I want to make sure that if there are any parasites or anything, I want to eliminate them before I move Levi. I've looked online, but there are conflicting statements ("use bleach" / "NEVER use bleach" etc). What should I do?
Also, I have a filter and a heater in the tank. The lady at Petsmart told me NEVER to use a heater but my old fish LOVED the heater and never had a problem with it whatsoever. Also, I have a filter in the tank...I've read that bettas don't like filters because the current can be too strong for them to swim against. Can they live in a tank without a filter? Everyone tells me different things!
Anyways thank you so much for any help or adive you are able to give me. I would REALLY appreciate it!

That brings me to my question - I have another betta, Levi. He currently has his own tank but I really hate it and it's a strange shape that doesn't allow room for many decorations or anything. I really hate that tank. I wanted to move him to Flounder's old tank, but I don't know exactly what killed him, so I want to make sure that if there are any parasites or anything, I want to eliminate them before I move Levi. I've looked online, but there are conflicting statements ("use bleach" / "NEVER use bleach" etc). What should I do?
Also, I have a filter and a heater in the tank. The lady at Petsmart told me NEVER to use a heater but my old fish LOVED the heater and never had a problem with it whatsoever. Also, I have a filter in the tank...I've read that bettas don't like filters because the current can be too strong for them to swim against. Can they live in a tank without a filter? Everyone tells me different things!
Anyways thank you so much for any help or adive you are able to give me. I would REALLY appreciate it!