I used to have 8 but one jumped out and another 2 died from some sort of contamination so I'm down to five with one of them being sick. They are great little creatures though. They're coldwater just like goldfish so no heaters for them. 10 gallons per Axolotl, NO gravel or rocks that they could swallow. Easy on the lights because they have no eyelids and they need to have a little cave or something to hide in. Really cute and snappy creatures.