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.