i have this green caterpiller like thing on the bottom of my tank and has been there for the last 4 hours and happy as a bug, do these exist in tanks??
One time I bought some live plants at my LPS. I started noticing that every day there would be pieces of the plants floating in my tank. Finally, whole sections of the plants seemed to be falling off. I blamed it on the fish for the longest. Then, one day I saw a tiny yellow catepillar about 1.5cm long munching on my plants!!! I removed the catepillar and found a couple more several days later. I have no clue what they were...but, obivously it was a type of catepillar that could live underwater.
its a caterpillar slug lol. It can live underwater. There are some aquatic slugs that will munch on your aquarium plants. But don't try putting garden slugs in because they will drown.