Thusly "Dan White" Spake Unto All:

I got two small oto's yesterday and wanted to be sure they would eat flakes
if there weren't enough algae. I had what I now believe was an oto (larger
one) a month ago (the store had it labeled as an SAE, which it surely
wasn't). He was doing nicely for a couple of weeks and then he turned up
dead. I assumed it was from not eating as the day after I got him the tank
was clear of all algae. Maybe it wasn't starvation

Oh, it probably was.

Anyway, yes, otos will eat flake - if the flake is allowed to settle
on the bottom, and stay there for a significant amount of time, often
hours, when the oto may finally decide it is harmless and worth
checking out.

They're about the least competitive fish there are when it comes to
feeding, so if you're keeping them with reasonably competitive fish,
then you may need to device some cunning plan to make sure there's
something left for them. Pellets sometimes work, unless the other fish
like them. Or vegetables. Other fish generally don't eat vegetables,
and Otos will eat e.g. brussel sprouts, salad or zucchini once it's
been in the water so it's they've become soft & soggy.

On a side note I was looking at a tank of oto's the other day. Some of them
had a black stripe down the body that was very straight and clear. Others
had kind of a black stripe but it was like there were black dots just above
the line and touching it, and the line wasn't as distinct. Is this a
male/female thing?

No, different species. Females can be separated from males primarily
by being bigger and plumper; when they're full of eggs *much* plumper.

As for WHAT species... www.planetcatfish.com has pictures of all the
commonly available species of Otocinclus in their database; also check
Hisonotus and Parotocinclus - they're commonly sold as otos too.