Hey, I have 2 otos in my 20 gal community tank. One is large and looks like she ( he? ) might be full of eggs. It has been this way for a little while. What would a pregnant oto look like? If it helps, pictures can be posted.
Egg layers can be gravid, and that may be what your fish's condition is. Otocincluses are egg layers and thus never experience pregnancy, so I don't know what a pregnant oto would look like. Female otos do have a much fuller belly than males do regardless of whether they are carrying eggs. Here is a video purporting to show breeding behavior for visual comparison to your oto's condition. A nicely rounded belly is indication of getting enouth to eat, but the belly bulge in the video is beyond that.