Hey all--I'm definitely a hobbyist-level fishkeeper, so bear with me if I'm doing something blatantly stupid.
I recently (a couple months ago) set up a 10-gallon freshwater aquarium. This is my first real "fish tank" (have also been keeping a fiddler crab in a separate habitat) since I was like 10 or 11 (when, let's be honest, it was really my mom's aquarium in terms of who cared for it.)
I cycled it w/o fish and added the first inhabitants slowly over the course of the next month. Everything was going really good. Then the following chain of events occured:
- My fiddler crab had been living with two platies. This was going nicely until there was eventually an "encounter" that resulted in a platy getting clawed and killed. I decided to move the surviving platy (who was cowering under a rock at this point) to the "big" tank.
- The platy did OK after a few days but I didn't like the idea of having a lone platy. I went and bought two more--one of them a "hi-fin".
- They didn't seem distressed or ill, but the original platy, and also one new one, died within a week. (All of my other fish were still fine.) Only the hi-fin was left.
- At this point, my dwarf gourami began chasing the remaining platy around the tank incessantly. The gourami had not done this to other fish previously. I thought that gouramis were supposed to be docile to a fault, so this outwardly-aggressive behavior was very surprising to me.
- I read up a little more and found that most experts recommend keeping gourami in pairs. I thought problem solved... two gouramis=better behavior. So I got an opaline gourami.
- The addition of the opaline gourami changed the tank's dynamic, but not in the way I wanted... now the opaline gourami chased the platy even MORE single-mindedly than the dwarf had previously. And the dwarf began (mostly) ignoring the platy and instead making charges at the opaline gourami and, now, my cories.
- The platy seemed healthy but I had to assume she was getting extremely stressed at this point. I moved her off to a holding "bowl."
- Behavior in the tank became more or less peaceful. The dwarf gourami would still occaisonally charge the smaller opaline and the cories, but not to the point that it was a problem for any of the fish.
- The platy's holding bowl was non-filtered. I simply don't have the means to get another aquarium setup for one fish. The water got bad quickly and I had to make a judgement call--what was worse, the previous stress or the new water conditions? I had to move her back to the big tank.
- Upon returning the platy to the tank, the behavior resumed. I have no idea what to do.
In terms of water conditions, we're at about 76 degrees. The only quality issue... I have some driftwood (ZooMed Mopani) which is only a few months old, so still gives off some tannis which discolors the water and lowers the pH over time. I do a 3/4 water change twice a week, which seems to control this.
Configuration-wise, I have two caves plus the driftwood, which is also cave-esque in several spots. Live bamboo in each corner and a decent patch of "flame moss" on top of the driftwood. Also in the process of growing a lily, but this isn't really adding anything to the landscape at this stage in its growth. All in all, there should be plenty of "territories" available.
The full list of tenants...
1x Dwarf Gourami
1x Opaline Gourami
5x Zebra Danios ("glofish" type)
2x small cories
1x "Hi-Fin" Platy
Any feedback would be appreciated. Do you think she'd be better off with the fiddler crab? Platies can outrun an advance by a fiddler very easily, but the crab only has to win one round to end the game...