comet goldfish not eating

Question
QUESTION: My comet, Rin, won't eat. he was eating fine two days ago, but now he won't open his mouth. I change the water weekly, and the tank is a ten gallon tank with a filter. Rin is only about an inch and a half right now, but when he gets bigger I will buy a bigger tank. but Rin tries to eat, but can't open his mouth to eat, and I am afraid he may starve to death if I don't figure out what to do soon@ could you please help me save my Rin? he's my only companion here at college!

ANSWER: Unable to open the mouth seems like mouth rot to me. Mouth rot can be a cause of poor water parameters such as a low acidic PH or high nitrites, nitrates, ammonia.

I am sorry to inform you but Rin is in much too small of an aquarium right now. Comet Goldfish can grow several inches a month and it's going to grow past the size of that tank quite soon or permanently stunt which will lead to more problems. He needs a 75g with double/triple filtration. In a 10 gallon with such a high bio-load fish its impossible to maintain good water quality despite your water changes.

The best thing would be to setup a larger aquarium, cycle it, and put Rin in so he can have good water quality and less stress.

- Ash

---------- FOLLOW-UP ----------

QUESTION: the maximum size of an aquarium we can have here is 20 gallons, if I change the water more frequently, say every three days, would it be safe to keep him in a 20 gallon tank?

Answer
I totally understand how you are limited in college but I am afraid that a 20 gallon is not much better and no where near to close to the proper tank size. Is there any local ponds or stores you could possibly donate him to so he won't get stunted or catch diseases in the future.