[cliner]

I've had 5 rummynose tetras in my planted 29 for several weeks. Three weeks ago I added 5 Robertsi tetras to the mix. I removed 5 cobra guppies two weeks ago and soon after that the fish have been hiding near the back of the tank. Whenever I look at my tank it looks like there's nothing in it. The come out to eat then retreat. The hide along the bottom, at the back of the tank.

Any ideas why they suddenly want to hide?

My only guess is that the top water loving guppies were acting as dither fish?

 

[Shadow]

I do believe you are right. The guppies more then likely made them feel safer. Maybe try adding more tetras. Maybe with larger numbers they will feel safer

 

[cliner]

Thanks shadow. Will add some new top water fish.

 

[CrownMan]

I also have Robertsi tetras and they and they do the same thing. I did some research and found out that they are very sensitive to light and also hide in their natural environment. Occassionally, they will pop out and display the dark cherry colors and long extended fins when the males go into king of the hill mode. I have added some dither fish and my lemons now are out most of the time but the Robertsis always shy away from the light. I do see them out more when the lights are off.

 

[Kooka]

Tetras usually prefer a darker substrate, and subdued lighting with lots of floating plants.Your tetras miht be hiding because your tank lighting is too bright for your tetras taste, and/or that your tank is too sparsley planted. I have 6 phantoms in my 29 gal and they tend to avoid areas that are brightly lit.

 

[ringram]

I believe that most fish shy away from bright light. There's probably an evolutionary explanation for that, but I'm no scientist, so I digress. I can say that my harlequin rasboras and cardinal tetras come out more when I only have 2 lights on, as opposed to 4 or 6. They also tend to stay in the more shaded areas. If you've ever had Silver Dollars, you probably know that they are about the world's most skiddish fish. I swear, they would dart around like crazy when the lights would come on, sometimes hurting themselves. They're also characins, which are the same family as tetras. You don't want these in a planted tank, though, as it wouldn't be "planted" for long.