Platy sitting at top of tank

[23578]

One of my platys is constantly at the top of the tank in a corner and I don't know why. Ammonia and nitrites are 0, and nitrates are about 30. The temp. is about 74 and the tank is well oxygenated because I have an airstone and a filter. I do water changes at least once a week so I don't know why he is acting stressed. I had another fish last week that was doing the same thing, just sitting at the top most of the time, and then he died so I'm really worried that this'll happen to him too. He's not showing symptoms of anything and is eating normally so I have no idea what it could be if it is a sickness. Does anyone have any ideas or advice?

 

[Andy Sager]

What other fish are in with him?
How long have you had him?
Do you have salt in the water?
Is the fish eating at all?
Do you see any white stringy feces coming from the fish?

 

[23578]

There are 3 other platys and one molly with him.
I've had him for at least a year I think.
There's no salt in the water but I have some aquarium salt I could add if it would help.
He is eating normally.
I haven't seen any unusual poop so I'm assuming it is normal.

 

[Andy Sager]

There are 3 other platys and one molly with him.
I've had him for at least a year I think.
There's no salt in the water but I have some aquarium salt I could add if it would help.
He is eating normally.
I haven't seen any unusual poop so I'm assuming it is normal.

If the fish in question is a male and there is another male in the tank, he may be hiding from the other male because he is not the "Alpha" male. If this is a female, she may be getting ready to give birth so they usually become inactive and look for calm places to birth their fry.
If the fish is eating normally and you don't see any white stringy poo, more than likely the fish is reacting to the other fish. Watch for either fry or aggression from the other fish towards this one.

 

[huma-huma]

Are you currently dosing anything at all in the tank?

 

[23578]

I dechlorinate the water with neutral regulator when I do water changes and that's it. I don't add in anything else and I've used neutral regulator since I got them so I don't think it could be a reaction to anything.