I have a tank in my office(5 Gallon) w/ 2 Albino Corys at the bottom and a small Goldfish on top with the water fluctuating between 23C & 24C.
One is very active and likes to be seen and the other is (or was) very shy since I got them. I have (or had) them for a week and on Friday the shy Cory magically disappeared. I thought it was because he is/ was shy and hid in the plants or driftwood (as he usually does) but on today (Monday) he is not on sight, he used to go out when I fed them but nothing so I'm wondering if he could buried himself in gravel or inside the plant. It is not soft sand like gravel but heavy stone like gravel so I don't believe this happened. I checked on the driftwood and the Small Castle I had for them and even in the filter !!!! Please help, as I don't want to move the gravel unless I'm sure I'm not harming him.
My guess is that the poor guy had probably jumped out of the tank, cuz the cory sometimes takes fun in dashing to the surface to take a gulp of the fresh air.
I'm afraid the most likely scenario is that the missing cory is no longer a cory - it probably died, at which point it becomes "goldfish food". Goldfish are notorious omnivores, and will take any oppurtunity to eat just about anything they can chew.
If you have fairly course gravel, I can guaranteed that a cory has not hid itself in the gravel. If it's nowhere to be seen, it's probably because the something ate it.
If that was the case, and he died and the body was eaten by the goldfish, I read that a carcass would be there with the armor of the Cory that the Goldfish can't eat.
Sadly I moved very carefully the plants and in the bottom of one of them there was Pearl. It probably tried to search for refugee inside the plant and the gravel fell.