Large amphipods

[acshaw80]

I’m fairly certain these are amphipods but they are really big. Some are about 1”. They are hard to get a picture of but I’ve circled one here with a frag plug and an emerald crab for scale. I’d say this one when he was moving was about a half inch but I’ve seen some about twice the size. The color seems to be and alternating dark grey and light grey banding.

my question is should I have any concerns about them? I’ve generally understood amphipods to not be a nuisance other than eating some copepods but I’m concerned that they are so large they won’t have a natural predator in the tank.

 

[Eagle_Steve]

I’m fairly certain these are amphipods but they are really big. Some are about 1”. They are hard to get a picture of but I’ve circled one here with a frag plug and an emerald crab for scale. I’d say this one when he was moving was about a half inch but I’ve seen some about twice the size. The color seems to be and alternating dark grey and light grey banding.

my question is should I have any concerns about them? I’ve generally understood amphipods to not be a nuisance other than eating some copepods but I’m concerned that they are so large they won’t have a natural predator in the tank.

Can’t really tell, but google Gammarid Amphipods and compare the pics. I have some in my sump close to an inch when they stretch out. If they are those, they are a good clean up crew and a snack for fish.

 

[acshaw80]

Looks close enough to me. I do have a bunch in my sump as well that fall out of my mechanical filter when I clean it but they re much smaller.

 

[Tired]

Are you sure they aren't isopods? Isopods look like roly-polies/pillbugs, and amphipods (gammarids at least) look kinda like a half-curled-up shrimp.

Amphipods are good fish snacks and detritivores, but, without predators, can multiply to larger numbers and irritate corals. Big ones are known to chew zoas. They'll definitely chew stressed corals, and a large population of amphipods can turn a stressed-but-recoverable coral into nothing overnight.

 

[Eagle_Steve]

Looks close enough to me. I do have a bunch in my sump as well that fall out of my mechanical filter when I clean it but they re much smaller.

If not an exact match, look up isopod and compare some of the pics. @Tired is right about way too many possibly being a nuisance to stressed corals. But pods self regulate with available food, so keeping detritus down will help lower the population.

 

[acshaw80]

Are you sure they aren't isopods? Isopods look like roly-polies/pillbugs, and amphipods (gammarids at least) look kinda like a half-curled-up shrimp.

Amphipods are good fish snacks and detritivores, but, without predators, can multiply to larger numbers and irritate corals. Big ones are known to chew zoas. They'll definitely chew stressed corals, and a large population of amphipods can turn a stressed-but-recoverable coral into nothing overnight.

I don’t believe so base on google images. Mine have long antennas and move sort of like a shrimp. Very quick and squirmy.

 

[Tired]

Amphipods, yeah. Do you have anything that will eat any of them? The biggest ones may not get eaten, but their offspring should be snacked on.

 

[acshaw80]

I’ve got a flasher wrasse that’s a good 3” long but I’m not sure he could scarf one of them down. I’ve got a 50g tank with a clown, wrasse, and helfricki fire fish. Open to suggestions!

 

[taricha]

I’ve got a flasher wrasse that’s a good 3” long but I’m not sure he could scarf one of them down. I’ve got a 50g tank with a clown, wrasse, and helfricki fire fish. Open to suggestions!

I have had fish that would ignore them to the point they became problematic, and I've had jawfish dart out of their tunnel (which they almost never do) and dart halfway across the tank to get one that I shook out of some chaeto.
You can tell who it's a natural prey item for!

 

[Tired]

Anything with a relatively big mouth is a good bet. Watchman goby, maybe? Rooster waspfish would be great, if you can get ahold of one. They're venomous, but not dangerously so to humans, and pretty easy to keep. Kinda like a perching goby.

Jawfish are cool, but need an area of deep sandbed, so I would pick something else unless you have an appropriate area for one.

 

[acshaw80]

Anything with a relatively big mouth is a good bet. Watchman goby, maybe? Rooster waspfish would be great, if you can get ahold of one. They're venomous, but not dangerously so to humans, and pretty easy to keep. Kinda like a perching goby.

Jawfish are cool, but need an area of deep sandbed, so I would pick something else unless you have an appropriate area for one.

Wow the rooster waspfish is so cool looking. I’m going to keep my eye out for one. So amazing

 

[Tired]

They're fairly rare to see for sale, unfortunately, but are great fish. And no gammarus amphipod is going to get large enough for a rooster waspfish to pass it up!