I have a 17gal tank with 10 adult guppies, 4 cories, plus guppy fry. I recently lost a guppy (to old age) and didn't find the body - I assume it was eaten quicksmart. However, I now have an ammonia spike of a little less than .25ppm, and have lost some fry (which was what prompted me testing). I am going to take the tank apart tonight and see if I can find any remains contributing to the problem (and do a big water change), but I also know that the tank is pretty full. Do you think it's too overloaded to maintain, or is it just the death(s) fault?
In addition, I'd like to add a couple of otos to clear the algae on the glass, and I really don't want to be having ammonia spikes with them in the tank. Do you think it's possible to add them too, or is that just way too much? I plan on maintaining the adult guppy population at less than a dozen by taking excess to the local pet shop.
EDIT: Here's a pic of the tank - I have since removed the rotala and replaced it with more hygro, and planted more of it along the back (to suck up the nitrates).