columbian shark having problem?

[snugglecat]

I have had 3 columbian sharks in my tank for the last month while I am preparing to install my new 90 gal tank and one of them has started to settle at the bottom, inactive for long periods.

Ammonia, nitrites, nitrates are all 0, temp 76, pH 6.8. It is a 28 gal tank that has been set up for several months now. I have been using 2 waterfall filtration pumps to give a good current for the sharks. I am currently sitting at about 22" of fish in the tank, which is more crowded than I like but they will have to wait a bit until I get the new tank cycled.

The tank is cleaned/vacuumed and 1/3 of the water removed every 10 days or so. Nothing has changed in the tank since I added the sharks.

They get shrimp pellets, veggie wafers (for the pleco), blood worms, flakes, krill and tropical granules (I alternate the surface foods giving 2 types per day for variety)

Any suggestions why this sharks is settling in one spot (same spot all the time) while the other 2 are active?

 

[rich311k]

I believe Columbian Sharks are brackish water fish. Especially as they start to age. Is your tank planted you should have some kind of nitrate reading?

 

[snugglecat]

I redid my test just in case I had a faulty strip or mistimed. Everything is showing the same as before except the nitrates are now listing as 3 ppm. I have been keeping my salt levels higher than I used to, but I don't know why only one out of three would be having a problem.

 

[rich311k]

He might be older or more sensative than the others or it could be something else. You should get a liquid test kit.

Is the fish eating normally? Are the other two picking on it?

You need to add marine salt not table salt to make them happy.

 

[snugglecat]

I have been using a liquid nitrate test and pH test and strips for the rest as recommended by my lfs. The fish seemed to be eating like is usually does and the others are avoiding it completely. I have always used the correct aquarium salt depending on the type of tank I've run over the last 10 yrs.

Any other suggestions? Should I just keep tabs on him for a while? I appreciate the advice.

 

[rich311k]

I would just watch him no sense trying to treat for an unknown possible ailment, if he is eating and showing no obvious signs of disease. The liquid tests are better in my opinion, the strips are not as accurate and more expensive in the long run.