u/hunterlikes1

I am a beginner with a freshwater 20 gallon planted tank. It has 6 corydoras, 4 shrimp, and 2 snails. I recently brought home 5 von rio flame tetras. Yesterday, I woke up and one of them was nipped at so badly it didn’t have any fins or eyes. This morning I wake up and one of my shrimp is split down the middle and eaten and ANOTHER tetra is nipped badly. I was supposed to have a betta community tank but I’m scared to purchase a betta with these in my tank. I don’t know what to do. Do I take them back to my LFS? It’s making me so sad :/. They are extremely aggressive and honestly I’m afraid they’re going to attack my corydoras.