a panther might get a little crowded in a 125 but he will be ok in there. in captivity, the largest i have seen was 26". also, get rid of the ray, he needs at least a 300 gallon tank. what is a blue sturgeon. the smallest freshwater sturgeon i beleive is either the sterlet or shovelnose sturgeon, both reaching around 42". do you know the scientific name of the blue sturgeon? i have never seen or heard of one, but i would think, it being a sturgeon is too large for your tank. bo