Gold gourami resting at bottom

Question
Hi there,

I will try to be as detailed as possible here.  This is my first aquarium so I am very new...

We have a 30 gallon tank
4 tiger barbs
1 banded gourami
1 gold gourami
2 fiddler crabs
bio wheel filter

I just tested the water and this is where it's at:
pH- somewhere between 7.8 and 8.0 (higher than before)
Ammonia- somewhere between .25-.5
Nitrite- around 2.0
--also--
Nitrate- 20
Hardness- 300
Alkalinity- 300 (MUCH higher than it was before...)
20-25% water change every week
approx. 6 gallons replaced on average

I'll start from the beginning...
The first fish we added were the gold gourami and the banded gourami about 6 weeks or so ago.  One week later, everything was fine and we added the 4 tiger barbs. Still fine.  The next week, we added the 2 fiddler crabs and 2 iridescent sharks...5 days after adding the sharks I noticed what I thought was ick on one of the sharks, just 3 little white spots.  I waited until the next day to be certain it wasn't just something stuck on him, and sure enough there were more, and also a few on the other shark and a couple on the banded gourami.  The other fish weren't showing and signs.  The following day I bought jungle ick clear and began treatment.

I used a half dose because of the scaleless sharks, and the next day the ick was no longer on the gourami, and seemed better on the sharks.  The next day I put in another dose, and noticed that the sharks weren't really interested in eating.  3rd day, 3rd dose, sharks were getting worse, with fins ripped and ragged.  4th day, (yesterday) 4th dose bad news...The sharks were really acting strange swimming vertically at the surface thrashing their heads around out of the water.  Needless to say, I became very worried...An hour or so after I put the 4th daily dose in, the larger, first affected shark was really not doing good, sitting on the bottom of the tank, with more white (but not ick) stuff on it's body.  This morning the large shark just looked awful...white all over especially around the gills, and the tiger barbs were nipping and butting into him.  The smaller shark looked much better than the larger one, but was still wildly trashing about on the surface.  I called the pet store and asked if they would take them back and see if they could nurse them back to health.  I brought them in earlier today.  I would just hate to see them die...I hope they make it.

So, here's my current observation...
When I got back from taking the sharks in, I did a water change, and added start right and conditioning salt.  After the water change, I noticed that the gold gourami was sitting on the bottom of the tank.  I put my finger in front of him on the outside of the tank, and he swam away, but continued to make his way to the bottom of the tank.  After sitting and watching for a while, I noticed that he would come up to the surface and take a quick gulp of air then kind of float back down to the bottom again.  He's been doing this for the past few hours now.  He ate when I fed them, and looks just fine, but I'm a bit worried at this odd behavior.  Then again, I might be reading more into it because of the whole shark issue.  Do you think something is going on or is it somewhat normal for a gold gourami to do this?  Also, is the water too alkaline?  It really changed in the past week.

Any insight you could give would be great!  Thanks in advance!

Answer
Hi Noralee;

I think this is all a result of "New Tank Syndrome", also called the break-in period or "Cycling". It lasts about 6 weeks or so. Ammonia and nitrite are elevated and are really stressing out the fish. They cause irritation and burns on the fish that can become infected. The ammonia was the first one to rise and now the nitrite is taking it's turn. Make a water change of 25% every couple of days to help keep them lower until they fall to a tolerable level on their own. Once your tank is fully finished with this break-in period the ammonia and nitrite should be "zero".

The pH is actually okay. Tap water often rises a bit after it has been in the tank circulating around. It is best not to try to alter it anyway. Alteration of Ph causes fluctuations that are more harmful to the fish than letting them get accustomed to the higher level. If the pH is continuing to rise and goes over 8.2, I would suspect that your aquarium gravel or your decorations are causing it. If you have shells, coral, marble, dolomite, or limestone in there you should take them out. They all add minerals to the water, causing the pH to rise.

The gourami may have a swim bladder problem related to the toxin poisoning. Hopefully he will feel better again once the toxins go down. Here is a link to my article about new tanks to help you know more about what's been going on in there;

http://www.xanga.com/Expert_Fish_Help

You might want to reconsider keeping iridescent sharks in there in the future. Those guys are actually a catfish that get to be about 3 feet long. They will get large enough to eat your other guys, and we don't want that! Yikes! Here is a link to more info on them;

http://www.scotcat.com/factsheets/pangasius_hypophthalmus.htm

I hope things get better soon...

At Your Service;
Chris Robbins