That's pretty hard water, I wouldn't do Tetras. Your water is actually extremely hard, even harder than mine and I consider my water quite hard.
Up the number of girls if you can, spreads out the aggresison, maybe 10 or so. You have four Cories in there right now I suggest upping the number to 6 or more, preferably 8 or 10 (but actually Cories are better in softer water, highest recommended for them is 12dH, but you already have four, so. . ) Also Mollies are great for your tank since your water is so hard, maybe increasing the numbers of Mollies too. Around 5 or so, remember to keep a 1:2 ratio, for every one male get two females, this will make sure that the males don't just bully one of the girls to death. Swordtails would also work in the tank, but since you're considering on re-homing them I wouldn't get any more of them.
Yes as everyone has said, seriously try to re-home that common pleco they get so huge, she seriously needs a bigger home. If you're able to re-home her you can increase the numbers of Mollies and Cories, along with more female Bettas.
If you don't want fry you can do all female mollies. Then you can mix sailfins and lyretails, and other forms. Normally mixing sailfins with other types is not recommended due to cross breeding, but the females will all be happy together.
Edit- just read on TFK that yours is a male. You can do all males, but, like a betta sorority, I would do minimum 4 males as with 2 they can easily be picked on.
I see. So swordtails would work well in my tank?
I'm debating on whether or not to give them away. My friend's swordtail died and I was thinking of giving her mine... maybe I can give her my female sword that isn't really accepted into the group and buy a few more females.
Are there any other kinds of fish that would work in my tank?
I'll go to my LFS next week and make a list of their stock from both stores and maybe we can work off that too.
As for the pleco is to give it to my neighbors for their pond. The only problem is, the neighborhood kids threw rocks at and killed their koi fish.
My mom has 75 gallon that she has way over stocked with 2 common plecos and a tigger oscar.
I can post some pictures of my pleco. I'm not sure if its a common pleco or not.
Livebearers, platy, guppies, endlers livebearers, mollies. Swordtail is up to you, if you want to keep it I would buy 2 more first...
The only other hardwater fish are certain rainbows; such as fork tailed blue eyes, but they are sensitive and need great water quality, plus they'd be skittish with all the tough fish in the tank.
Another one is x ray tetra, it's a tetra that is fine living in pretty much anything. That could probably work well. Posted via Mobile Device