i just now realize i only mentioned the betta. first off, thank you, everyone, for being so polite and helpful for what is, i'm sure, a newbie level inquiry. in the 10 gallon, for about 5 weeks. i have Chorizo, 2 nerites and a small group of espei rasboras. i remember putting IN 2 stone catfish (tiny little guys) but i have only seen them a very small handful of times since then. my parameters are good and the nano sponge was doing the job, i just wanted to relocate it to a smaller tank and give this one the better suited size. i've been away from the hobby for close to 20 years, and everything i used to know is no longer what would be best and i'm trying to learn the newest, most fish-friendly techniques. btw, this low tech sponge filter stuff is amazing.