I set up my 29 gal on Dec. 20. After running it (with plants and rocks from 2 other smaller, established aquarium). After a week or 2, I added the 6 corys. (No bettas yet.) One cory died overnight; I returned it for another. After a week of happy corys, I added first 3, then another 3, then 6 betta girls. I should have used a hospital tank, but this was not an established tank, so it became the hospital tank. 3 corys overnight, the rest the next day! I then lost 2 bettas (imports) in short order. With that, I broke down the 29 gal. 100%. I couldn't risk that there was something toxic in the big tank so all substrate, plants, snails, and decor was disposed of. I removed the remaining girls to a sparsly planted 10 gal, where they have been for 3 weeks. I lost one more lovely import a few days later. Now, I have the 29 gal replanted & ready to go, but I AM SCARED!! Everyone in the 10 gal is doing so well...
4 bettas: Butch, 3-year-old violet male PK EE & 3 girls in a 30 gal sorority. I do not name the girls anymore! 1/2 of them die within a month.
30 gal: 9 Oto cats, 4 Ocellifer cats. Inverts: Cherry shrimp & 2 assasin snails.
10 gal.: Butch, his 5 oto cats, 3 assasin snails, and a few snails the assassins haven't caught.