All sturgeon require cool waters though some tolerate up to 78 F, the smallest are only 2' long but if you have one of those (they are both from the Amur river) you are looking at several years in prison,. Sterlets average 3' as adults , 1000 g ponds 2' deep at 65 F- 70F max is recomended. American sturgeon vary alot and most are protected, the common Pacific, or White Sturgeon is currently limited to 2 a year between 42-60 inches, over and under cost you big time bucks if you are caught, but if you register a legal caught fish theylet you keep it if it out grows the limit. (they can rewach more than 16') Registration is free as long as youy have a fishing liscence.