IMO, 2.5g is too small for tank mates.

 

A couple ghost shrimp thats about it. Cherry shrimp are betta snacks and so are ghost shrimp but they're likely to be eaten too

 

I like ghost shrimp. Yes, they may be eaten, but then they are cheap and your betta gets a fun protein snack. If not eaten, you get a cleanup crew. I would try maybe two at the most. A LFS might carry cherry shrimp, I have never seen them in a chain store. You can order them on line, but I would not risk them unless you knew for sure your betta would not eat them. Corys and ottos like to be kept in schools, too small for your tank. And I believe an ADF requires a minimum of 2.5 gal itself, and the betta may not like it either.
=^._.^=

 

Agreed. Start with 2-3 ghost shrimp and see how the betta does with them. Most small shrimp will be eaten, but ghosts stand a chance, plus they're cheap. (Quite funny little characters, too)

You could push limits a bit and add a couple of neon tetras (again, if he tolerates tank mates, only one way to find out!). I had that combo (plus a couple Nerite snails) for a while and it was fine, but feeding was a hassle because the betta was a food pig and the tetras wouldn't eat from the surface or the ground, only mid-water, so getting them fed while keeping the betta away was an ongoing hassle.

An ADF would be cramped in there with a betta, they should really have 3 gallons (and no fish) or bigger.

 

I tried two ghosts shrimp with my male betta in a 2.5gal. He killed them both on the 2nd day

 

Will nerite snails eat off the bottom, or will they only eat off the glass? How do nerites do with lice plants?

 

No idea about lice plants, not familiar. Nerites cruise around the whole tank, every surface, even your plants! (eating the dead bits and any algae, they don't eat the live plants)

 

A 2.5g doesn't provide many options. No fish, no snails (even a Nerite puts out too much bioload for a 2.5g). If your Betta doesn't eat your shrimp they'll soon succumb to erratic water quality. If you're using a Tetra 3i, I know your tank isn't cycled. Shrimp need a cycled "established" tank.

Betta don't need company. Don't force the issue.

Or, get a bigger tank. ;-}

 

I don't agree. A betta and a nerite are just fine in a 2.5 gal tank. And ghost shrimp are relatively hardy, could easily be fine, as long as temps are stable and water is kept clean. Other species are a gamble, agreed.

 

I have the same setup on two tanks. The one tank has 3 ghost shrimp and an older baby betta. The ghost shrimp have been in there over 4 months and are thriving. They can be very nasty at feeding time though. They attack each other and will attack the betta if he goes for their food. I have to watch very closely when I feed.