How big can ghost shrimp get? And why are they so aggressive?

[FlakRiot]

I recently started a shrimp tank to prepare for a betta that I am going to get from my friend who happens to breed bettas. I bought 10 for $2 (but i really got 11 shhhh) because they were feeders. Supposedly they are ghost shrimp. Two of them are almost 2 inches long and they already ate the stalks off of my gold mystery snail. They are all extremely aggressive. I feed them well have been doing 10% water changes every other day. The tank is lightly planted with javafern, moss ball and a banana plant. Snail is currently in an isolation chamber in hopes that it will recover. Is it possible that these aren't ghost shrimp. I have had them for one week. They are starting to turn a more milky color all of them have molted at least once. They were perfectly clear beforehand. Some even have developed white strips along some of the crevices of their tail end. I got these shrimp because I have read in many places that they make great tank mates but a part of me wants to get rid of them. Or find the ones eating my snail and get rid of those specific ones. They are all very active and none of them seem to have health problems. They do seem to be more active during the day, which is weird. Could these not be ghost shrimp at all? I'm so lost. What should I do? 3 of them seem pretty calm. Always chilling under around and on the java fern(these three are still less than an inch). The rest....worry me.

 

[joeychizzle]

They might be macrobrachiums. If that's the case then they will literally snatch any living thing they can and devour it. Every tank I ever tried to house them in, they conducted genocide. Bettas, otos, snails, shrimp, crabs, etc. They are crazy evil and shouldn't really be kept with other species. Hell I've seen them eat each other when they were hungry enough.
If they're ghosts.. well then maybe you just got a particularly aggressive batch.
I personally recommend swapping them out for some cherries, tigers or sakuras.

 

[cre8byconstance]

My sister got a ghost shrimp a month or so ago that was very aggressive. He kept grabbing onto her beta and pulling away from the food when she fed them. She had to rehome him because of his aggressiveness. Not sure if that's normal for these shrimp or not though.