IMO-10gal tanks are not big enough to support a proper school of Otocinclus catfish long term....even though they are small fish-IMO 10gal just isn't big enough to meet their needs....they need a good amount of swimming space and tend to do better with more natural foods-granted a closed system will never support nutritional needs fully and they will need supplemented feeding-but these guys are active and need room-more space the better and the larger the school the better.....
They can be sensitive to water quality, medications, extremes and tend to do best in tanks that are mature and heavy planted with lots of water movement with temp in the mid/high 70'sF range.....
A really neat species to watch zipping all over the tank-chasing each other and spawning-however, it can be difficult to get eggs to hatch and fry to survive...