New Fish but a problem with the Water?

[Puffy]

Hi Guys,

I'm new to your forums but have had tanks all my life.

The main reason I signed up was because of this odd situation.

So usually, if I need to add any fish or shrimp, then there is no problem.

I bought a few new fish for one of my tanks but now all of the fish constantly swim to the top!

I started this tank about 3 years ago and although it is one of my smaller tanks, I have never had a problem with it.

It is almost like they are no longer getting proper air circulation?

I increased the air supply by 30% a few hours after I noticed the problem, but they are still skimming the top, which they have never done before.

I put the airflow back to normal with no change to their behavior.

I'm thinking that the water from the shop is bad and that I need a big (50%) water change?

Any ideas are welcome because I have around 40 fish in the tank and I only added 6.

[mommy1]

Water changes never hurt. Have you checked the ammonia level since adding the new fish? Adding new fish to an established tank can throw parameters off for a short while until the bio-filter catches up to the added bio-load.

[Puffy]

It has been 3 days of the fish water skimming.

That's why I'm worried!

No deaths or any kind of rot or bloat.

My shrimp in the tank seem more active than normal but possibly because there are no fish going down!

[mommy1]

Lol, your poll options make me giggle. Check the parameters, it takes a few days for ammonia to go back to 0ppm. If this is the problem you need to do water changes to keep the ammonia down to tolerable levels for the fish.

[Puffy]

My poll options say exactly what my fish are thinking!

A water change is the first thing I'll try.

I usually let the fish and water (Plus the stuff that is in it) settle for a day or so, but I have never had this!

I have never had a problem with ammonia level before! Especially after adding a few fish!

[Goes to 11!]

You left out some relevant info:
Tank size? [Smaller tank]
Actual stock is...? [40 fish..]
Filtration?
Water parameters?

It's hard to speculate on the issue [or issues] without these facts at hand..Just saying.

[Cliff]

It has been 3 days of the fish water skimming.

+1 to the above comments / requests for water parameters

Also, I'm not to sure what you are referring to in the above statement. Could clarify that a little more please. Or are you referring to the fish just staying at the top of the tank ? Also, what do you have for filtration on this tank ?

[imma24]

Also, could it be possible that the fish you purchased for your tank prefer the top of the tank?

Don't forget, there are fish that "hug" the top and some are all over the place. My danios preferred the top even though they wandered, my guppies are the same way.

[CrunchyLeaf]

I am going to just guess blindly that it is a water quality issue in an overstocked tank. You say this is one of your smaller tanks and it has 40 fish in it? That just seems like a lot on the surface without knowing what kind they are, but maybe this is an larger tank than what i'm picturing and you have smaller schooling species.

Do you have a test kit for ammonia, nitrite and nitrate?

Also did you add the water from the pet store in with the new fish?