Small critter walking back and forth

neutralreefer · Mar 20, 2021

Please take a look at the video and help me find id. The one you can see is maybe 3 mm (0.1 in) long, but there are more of them in my tank, mostly much smaller. They all hide in rock, quickly come out and reverse back to the same spot. I saw one picking a grain of sand and taking it back to build something on the entrance. Also, they all have quite distinctive white dot on a back. The only crustaceans I have in my tank (that I'm aware of) are hermit crabs and copepods.

DeniseAndy · Mar 20, 2021

Could be a baby mantis? Did you get live rock recently?

neutralreefer · Mar 20, 2021

Yes, they could hitchhike on corals.

Alvaro_Spain · Mar 20, 2021

It doesn´t seem to me like an amphipod. My guess is same as DeniseAndy or even a lobster larva

mtfish · Mar 20, 2021

Alvaro_Spain said:
It doesn´t seem to me like an amphipod. My guess is same as DeniseAndy or even a lobster larva

A mantis shrimp at that size would already have a flattened look to it. The more I look at it the more I think it is a tiny spiny lobster. Keep us posted if you keep seeing it to figure out the mystery.

Alvaro_Spain · Mar 20, 2021

mtfish said:
A mantis shrimp at that size would already have a flattened look to it. The more I look at it the more I think it is a tiny spiny lobster. Keep us posted if you keep seeing it to figure out the mystery.

Yeah, I think I see the pincher and crusher claws too.

Anyway I´d love to have it in my tank

alpha199 · Mar 20, 2021

That's pretty cool! Post another video next time you see it!

neutralreefer · Mar 21, 2021

Three more videos (took me half an hour to catch them). They are active during a day.

Alvaro_Spain · Mar 21, 2021

Those last videos seem gammarus to me.

mtfish · Mar 21, 2021

Alvaro_Spain said:
Those last videos seem gammarus to me.

If the last videos are of the same thing, then I am in agreement. Looks like an amphipod.

neutralreefer · Mar 22, 2021

Oh that's good. I wouldn't know what to do with so many lobsters

Now, what can I add to 65 gallon tank to control their population? I guess clowns and cardinals won't be interested in chasing them..

mtfish · Mar 22, 2021

neutralreefer said:
Oh that's good. I wouldn't know what to do with so many lobsters Now, what can I add to 65 gallon tank to control their population? I guess clowns and cardinals won't be interested in chasing them..

Unless they are just annoying to look at, I would just leave them alone. They are part of your CUC. They should self regulate unless there is a lot of uneaten food or tons of algae for them the graze on. Not sure which ones for this size tank, but wrasses will pick them off. Check out the wrasse lovers thread in the fish forum.