I was watching my 29 gallon tank just now and noticed two of my three upside down catfish are extremely swollen. I'm not sure if they're gravid, bloated, or possibly something else? I don't know exactly how long they've been like this since my upside down cats tend to hide in a driftwood cave until I turn the tank lights off. Water parameters are 0 ammonia 0 nitrite and 5 nitrate. They're both eating and swimming normally. I've had them in this tank for over a year. They eat fluval bug bites and tetra shrimp wafers. Is this something to be concerned about? Thank you.