How can I tell if my cardinal tetras are eating?

I got six cardinal tetras about a month ago as the first set of fish to go into my 20-gallon tank. I am worried about them because I never see them eat! they are nothing like the other fish I've had where they immediately go to the top of the tank when I feed them. I got semi-floating food for small-mouthed fish since I read that they eat towards the top of the tank. I think they have grown a little bit since I got them and their colors seem better than before too. I am going to get brine shrimp and or blood worms this weekend for them to diversify their diet a little, but does anyone else have this problem? is there any way I can be sure they are eating? They like to hide when I walk up to the tank so I try not to be nearby right after I feed them. any tips? I am worried that it is because my tank isn't planted enough. I've attached a photo and I am working on making them a ceramic hide this week too.

 

I got semi-floating food for small-mouthed fish since I read that they eat towards the top of the tank.

One mistake: The are midwater feeders. Not top or upper 3rd. I'd feed high quality pellets.

I am going to get brine shrimp and or blood worms this weekend for them to diversify their diet a little, but does anyone else have this problem?

Just get the shrimp, bloodworms are not as healthy for fish as people think. Nutritionally junkfood.

is there any way I can be sure they are eating?

You will see it. Cardinal tetras are usually greedy feeders. The fact you don't see them eat may be due to the fact they are not doing well. The tank is a bit barren. They need more plants, more cover and more structure. Some rootwood perhaps and some twigs. And floating plants.
No caves, though. Tetras need cover from above, not caves. They never use those except in extreme situations.

 

One mistake: The are midwater feeders. Not top or upper 3rd. I'd feed high quality pellets.


Just get the shrimp, bloodworms are not as healthy for fish as people think. Nutritionally junkfood.


You will see it. Cardinal tetras are usually greedy feeders. The fact you don't see them eat may be due to the fact they are not doing well. The tank is a bit barren. They need more plants, more cover and more structure. Some rootwood perhaps and some twigs. And floating plants.
No caves, though. Tetras need cover from above, not caves. They never use those except in extreme situations.

Thank you so much! I was worried about the plants... what kind of floating plants would you recommend? I had duckweed in but it all died because it kept getting stuck to the sides of the tank. I put in pothos to help cover the top a little bit more and so the roots can give them more places to hide was that a good idea? Also just as I was typing this I watched one eat some food for the first time lol.

 

How to make floating flakes sink:
Pinch food, stick fingers in water, release underwater and distribute by rubbing finger and thumb together.

 

Way more plants will help a lot and also some covering on the back glass (such as a black background). Once your original 6 start eating, they might like 3-4 more cardinal tetras for a larger school.