Large Tiger shrimp holding down and killing small cherry shrimp.
So, tldr version: I have an ebi tank with 25 cherries and 15 tigers. Today I watched a tiger hold down a live cherry shrimp half its size and pick it apart. I moved the cherry to a seperate container where it moved around for awhile, then stopped, and its probably dead now. Im just posting to let people now that this can happen, because everything Ive read suggests that it wont, and that whenever it does, its actually just shrimp cannibalizing a recently deceased tankmate.
So, I have a large, 1.5 inch tiger shrimp in my 8 gallon ebi. Its much darker then the others and currently berried so she stands out from the rest. She tends to bully the other tigers, especially at feeding time, throwing them out of the way, and they happily move out of her way. She normally ignores cherries, they walk all over her literally to get at the food and she doesnt care.
Anyways, this afternoon I cleaned my 25gallon tank and noticed a large clump of algae coming off the overflow of two aquaclear filters. I scooped in up and threw it in the ebi to give the shrimp some vegetable food. Ive done this before, they usually swarm on it.
An hour later, I go to check if theyre eating it, and I see my big tiger holding a half inch cherry shrimp on its back, and picking at its underside, where the eggs would be kept if it was berried. There were no eggs left, but I was pretty sure this was one of my berried shrimp, as it was my reddest cherry and I was hoping to see some offspring from her. Anyways, I was dissapointed, thinking "oh that cherry must have died and theyre eating its carcass", but then 5 seconds later, the cherry started to wiggle its legs. I netted the cherry out and put it in a bucket with some tank water and a piece of mossy cactus wood from the tank, to give it somewhere to hide if its alive still, to make it more comfortable. It lay on its side, and wiggled the legs occasionally, but didnt move. It had two large white cracks on its back, as if it was trying to molt and break out of its shell. I left it alone for about 5 hours and just checked it. It had moved to the other side of the bucket, but is not moving any longer, and I doubt it will survive, if its not dead already.
(Some background information, this is my second attempt at shrimp keeping. I bought 25 cherries a year ago and they all slowly died over 6 months, due to my overfeeding, and feeding eclusively fluval shrimp granules. Im trying to not repeat that mistake, and Im feeding every other day, and I alternate feeding blanched zuchinni, cucumber, spinach, chunks of algae I pull from other tanks, and also fluval shrimp pellets, which they get maybe once or twice a week. )
The tank has 15 tigers and 25 cherries added just over a month ago. Currently 3 tigers and 4-5 cherries are berried. I can never see more then 10-20 cherries at a time, I assume because they are hiding from a molt, or just because I have lots of cactus wood and malaysian driftwood, plants, and places to hide. Now Im worried that these missing cherrys were just food for the tigers. If anyone is curious, the tank is an 8gallon ebi, temp is 75 degress, kh is 7, gh is 7, ph is 7.3, ammonia, nitrites, nitrates are 0. I don't supplement anything. Water changes are ten percent twice a week. I usually get 2-3 skeletons showing up the day after a water change due to moltings.
I've read a lot of threads of people suggesting that their shrimp are killing each other, and people respond and say the shrimp must have just died of natural causes, and then the other shrimp cannibalized the corpse.
I just wanted to point out that this can happen, I just saw it happen with my own eyes. Im not sure if this is just a super agressive tiger shrimp, or if its because she is berried and needed extra nutrients. Maybe I'm not feeding enough. Maybe the cherry shrimp was having molting issues and the tiger took advantage. Maybe cherry shrimp eggs are delicious and the tiger wanted a treat. I don't know.