Dwarf Crayfish vs. Dwarf Shrimp

[Ragnarok12]

I know this thread header probably reads as one of those, "Which one should I get, shrimp or crayfish?" kinds of posts.

WRONG

I just observed what I'm pretty sure was an epic fight to the death between my VERY pregnant carbon rili shrimp and my 1.5 inch Mexican Dwarf Crayfish. And by epic battle, I mean I'm pretty sure my crayfish just murdered my rili shrimp in cold blood (well techincally 78.2F blood, given my tank temp, but you know what I mean). It all went down in my 5 gallon planted desktop aquarium with the shrimp, the crayfish, a nerite snail, an amano, and a small school of kubotoi rasbora that have shown no interest whatsoever in the shrimp. I'm 100% positive I saw this rili shrimp swimming around the tank three minutes before, then I look back and the crayfish is trying to eat the body of this rili shrimp.

All of this to say, my question is this: Have people found mexican dwarf crayfish to be aggressive to pregnant adult shrimp? I was hoping to have a small colony of shrimp going in there with my crayfish, but if he is actually a shrimp murderer, then I need to kiss that dream goodbye. I'm actually really bummed because I'm now down to four rili shrimp and none of the others appear to be females, so that one pregnant one was likely my only shot at getting a colony going.

[Alesha]

I'm pretty sure it's a "if it fits in the crayfish's mouth, it'll eat it" kind of thing. He's just feeling hungry and found a snack that couldn't run away fast enough. 😔

I think in a tank that small, it would be hard for most things to get away from a crayfish. They really will eat most things. I think the snails are safe, since they have their own hide-out, and the fish should be ok, if they swim fast enough. But anything else is fair game. At least in the crayfish's mind.

I'm sorry for your loss. Maybe you could try him in a larger tank, so that everybody else has plenty of places to hide?

Alesha

[xXInkedPhoenixX]

So @Ragnarok12 did you change anything here? Any further shrimp murders? Just wondering. I'm thinking of options and always thought the dwarf crayfish was a cool animal- I don't have any shrimp so.... 

I'm actually kind of hoping they eat bladder snails occasionally or at least their egg sacks...

Edited October 17, 2021 by xXInkedPhoenixX

[Ragnarok12]

@xXInkedPhoenixX TBH I'm not sure that I have the best set up to give advice on the inverts. I did not not anymore shrimp murders from the crayfish, but in hindsight, I'm thinking that the shrimp may already have been near death. I've been trying constantly to keep inverts alive in that tank since July, and I am down to one cherry shrimp and one amano shrimp. The crayfish was actually really fun and relatively harmless, I think they are just opportunistic and if something is sick or exposed, they may take the opportunity to snack on it if it is at ground level. I can't imagine one catching a fish, as they are quite slow and have very tiny pincers.

You should be safe getting one, just make sure that there is sufficient mulm and biofilm to keep him fed. I started a different thread about a month ago to tr and diagnose why I can't keep inverts alive in that tank, and the answer I landed on is that I keep it too clean and free of biofilm. I haven't been able to keep an inverts alive in that tank for more than a month (aside from the immortal amano shrimp), and I think it's because they don't have enough to eat and the tank is not sufficiently seasoned. I don't feel I've mastered shrimp and crayfish keeping enough to give trusted advice, though, so take all of this with a grain of salt.

You should get one though, they are not too terribly expensive for one and they are really cool critters. No idea if they would eat shrimp eggs or not, but maybe?