Scared fish?

[Scrumpy]

My 33 gallon tank is ticking along nicely, and now I have a Moby Dick tank (about 16 l I think) that I've just set up.
I've put two tiny diamond tetras in there. It's not going to cycle as such because I've used a mature sponge from the main tank. I've put in plently of plants and places to shelter/hide.
The two tetras are very distressed. Hiding in the same spot at the bottom of the tank swimming very fast in that position. If I turn the lights on they dart about madly crashing into the sides (so I don't) and they haven't eaten since I put them in 4 days ago. I can't see anything obvious wrong with them. They just hate the tank (water parameters ok).
Any suggestions for making them happier/more secure please? I hate seeing them so unhappy and I'm worried they're going to die.  

 

[Avalon]

Check your water again (Ammonia, Nitrites, PH). Sounds like the water isn't quite right, possibly PH shock, maybe temperature differences. I have found in every instance of these symptoms I've experienced, the water was the problem.

 

[koolkatzfish]

If the water is okay, consider a couple more tetras, 2 does not make a school and they can be nervous, especially in new situations.  A friend gave me her lone neon tetra and he was very nervous and upset, I got him 5 more and he was happy as a fish in a school.  Over the years all but one neon has passed away, but since this guy is familiar with the tank and other dither fish he seems fine.  

 

[Scrumpy]

Thanks for the replies. Water still seems ok, but I'm going to do small daily water changes and see if it helps. I'm reluctant to get more fish since this is actually supposed to be my hosiptal tank so I can't fullly stock it (and shouldn't have anything in there really I know ). Still if that's the only way to cheer them up that's what I'll have to do in the end.
Thanks again.
Are diamond tetras known to be nervous?

 

[NTidd]

It also could be that there isn't enough bacteria in the tank yet for them, but more importantly that there aren't enough of them, a while ago I bought 2 silver dollars, and they would never come out so I bought 3 more, and now they are always in the from of the aquarium together.  Good  Luck.