I have a 8 gallon tank with a filter/heater.. and it's planted.
After cycling my tank (which took just a little over 2 weeks with the help of Nutrafin's Cycle
) I added 1 betta, 2 nerites (one is a zebra nerite and the other is a tracked nerite) and just recently placed 3 otos...
I recently lost a single oto - likely starved unfortunately... but he was in a 3g with the betta and snails while I was waiting for the 8g to cycle. The biggest issue I had with the oto (aside that they do like to be in a min schoal of 3) was that my betta was being territorial over the food... And I didn't have much room to try and hide some algae wafers.
I tried zucchini and even setting him in his own tank - but he just didn't make it.
Otos are more known for eating brown algae... so this time I'm changing it up with a different type of wafer, I have 3 now, so they should be socially happier, and I have sufficient covering (multiple pieces of driftwood) for them to escape to (and to hide the wafers at) You can also supplement with blanched zucchini, spinach, lettuce.. and you can also grow some algae on rocks in a jar outside in the sun.. and just cycle the rocks through the tank.
is a good website for info on the oto...
can help you determine bioload
A filter is a must for a 10g. You can cover the intake of whatever type of filter you get with panty hose to prevent any inhabitants from getting sucked in - and you want to find one that had adjustable flow.. I'm using the Marineland Duetto 50 - works nicely.. Also, the filter is what houses most of your bacteria colonies that process the nitrogen cycle.