Hi m8
If your going to get 3 Otto's try and get 3 with the biggest belly's , that way you know there well fed and are more than likely to survive, i bought 5 and have 3 left, while researching them i came across a few websites that stated that one of the reasons that Otto's can drop off unexpectedly is that there usually starved of algae in transit plus most shops tend to keep there tanks free from algae , also they said that if they are starved for long enough that there digestive system has trouble recovering thus making them less likely to survive..
the 3 i have left all have big bellies and have lots of energy

, they love croquette by the way
glad to here everythings going to plan m8