How do I know new tankmates are good with each other? How do I know they're not stressing each other out? What behaviour should I be keeping an eye on? And how can I know it's going well? And also, should I take the fry out?
Some background and further explanation for this:
boy Ciel has been nipping his tail recently and I've been trying to make him stop. I provided him with more top coverage, more plants and more places to hide, made sure the water is 100% okay for him, but it didn't seem to effect the small nipping. He doesn't do it anyhow drastically, I've seen other posts with bettas who nipped way worse in way less time. So in a different forum, we agreed it also might be just boredom. Since he does it just whenever he feels like it and only a little. I tried distracting him with floating toys and colors, but again, not to much effect. Today, I finally took a deep breath and decided to get him tank mates. I member suggested it to me and when I googled it, I saw that it helped a few people before. It keeps the betta distracted. Knowing his nature (curious, but also incredibly calm and gentle compared to my boyfriend's fierce betta), I decided to try and go for it.
I chose three Ember Tetras
. The lady accidentaly gave me a fourth one, a little fry which I am the most afraid for. Look how incredibly tiny it is on his hammock leaf!
I put them into the tank in their plastic bag and let him observe them. Then, when they acclimated to the water, I cut the bag open and let them swim out. It happened really smoothly and they seemed calm. He chased them around for a tiny little bit. I'd say for about 10 minutes. But he didn't ever seem agressive. He wasn't trying to nip them or dart at them even, I feel like he was just swimming after them to inspect them out of pure curiosity. He still occasionaly wants to take a good look at them, but I really don't think he's trying to attack. But it's been just a few hours and I feel like it's really natural for him not to know what's going on yet.
After two hours or so, they stopped being afraid of him. The Tetras stopped swimming in a school and spread around the tank a bit more. Ciel would just "pass them by" sometimes, looking at them, but not coming after them or changing his direction because of them. The tiny fry keeps hiding. I think I noticed him swim out about three times and each time, Ciel swam to him and scared him again.