Thanks for the info guys, not had much luck with these Geos though.. Checked the tank on Monday morning and the largest one (with the damaged eye) was dead with no signs of injury. Woke up this morning and the second largest one had died, again with no injury. This one had never seemed right from the start, was always hiding and sitting on the bottom breathing heavily. Tested water, ammonia 0, nitrite 0, nitrate 30 (was water change day, never gets higher than this and have since added floating plants to help keep them lower) and pH was 7.2. Smallest Geo has been fine from the start, swimming around and sitting through the sand happily, not sure if I want to spend the money on more now though..