tankmates for crayfish

Wow, um, you've got quite a dilemma with the restrictions there...I think that zebra danios may work, as they can swim quickly enough to get away, and they are cheap enough (please be gentle and don't flame me for that, folks...) that replacing them wouldn't be as bad as, say, replacing some of the "newer" Melanotaenia species (among many, many other species--almost every species of any fish would cost more!)

maybe a pair of butterfly fish would work, they are just about strictly surface dwellers, although they may eat the smallest of the crayfish (less than an 1.5 inches).

I wouldn't mix anything I didn't want to be a snack in with crayfish. Period.

i kept zebras with a crayfish...the population dwindled from 12........to 5 over a 6 month period before i finally lifted them to another tank. those crayfish can really sneak up on them, i guess, because there are few small fish faster than zebras.

the one fish i have kept successfully (for over a year now) with the crayfish is a large blue gourami (about 5 inches). they're in a 20g long tank, with NO PLANTS and only a couple low rock caves for the crayfish. because of this, the crayfish can't climb up and take swipes at the gourami, who very very rarely leaves the upper strata of the aquarium.

this was my especially mean male blue who proved incompatible with all other fish i had...personally, i think both the fish and the crayfish are terrified and bewildered of one another. both run away from each other.