The best way to keep P.hypopthalmus??

retro_gk · Post by **retro_gk** » 02 Jun 2003, 02:56

Hi all,
I recently visited someone who who has a 4'x4'x18" tank with two 18" P.hypopthalmus and 4 6"+ Koi in it. The tank stands on his verandah w/o any cover or lights. It receives about 2 hrs of sunlight/day and the water is very green with visibility of just about a foot. About once a week, the gardener siphons off 50% of the water and replaces it with fresh water.
Now for the interesting part........Those catfish are the calmest ones I've ever seen. Pangasius are very popular fish in this part of the world and all the others I've seen have been more than ready to leap out of thier tanks if anyone as much as lays a finger on the glass. Even those kept in ponds tend to be jumpy. These two fish however not only dont mind your touching the tank, they also tolerate the water being agitated, decor being moved about etc.
I wonder if this is due to their associating with the Koi or due to the fact that the low visibilty in their tank makes them feel more secure?
rahul.

Post by **Silurus** » 02 Jun 2003, 04:34

I think the owner just got lucky and managed to get naturally calm fish. Given that sight isn't very important to these catfishes and adding more ostariophysans increases the risk of stressing the fish becuase of all that alarm substance in the water when they are disturbed.

retro_gk · Post by **retro_gk** » 03 Jun 2003, 19:28

I was under the impression that pangassids were nocturnal/crepuscular. Therefore low light levels(as in this particular setup) would presumably make them more comfortable?

Post by **Silurus** » 03 Jun 2003, 19:32

Not really. catfishes are very sensitive to sound (like other ostariophysans), so something like tapping on the glass really spooks them, regardless of light levels.

retro_gk · Post by **retro_gk** » 03 Jun 2003, 19:49

If all catfishes are sensitive to sound, then why dont they all run scared?

Post by **Silurus** » 03 Jun 2003, 19:50

Because of habituation. And also because there are few natural loud sounds in their habitats.

retro_gk · Post by **retro_gk** » 03 Jun 2003, 19:57

So if I were to take a young catfish and expose it to sound/vibrations regularly, would it grow up to ignore them?

Post by **Silurus** » 03 Jun 2003, 20:01

Possibly. I think it also depends on species and possibly the individual (fish appear to have personalities after all).