9 gallon peninsula tank stocking with mantis shrimp

n.wennerae · Jul 2, 2026

I have an Eshopps Deskmate Florida 9G peninsula tank that I’m wondering what I can stock with. It currently has a some soft corals, a single N. Wennerae mantis shrimp (about 2in. long), and a clean up crew consisting of munnid isopods, astrea snails, cerith snails, and blue legged hermit crabs. Initially I did not consider getting any fish because of the mantis shrimp but I’ve had the mantis shrimp for a few months now and I doubt he would go after a fish. During the time I’ve had him he hasn’t killed a single clean up crew member. I have even tried grabbing snails and hermit crabs with tongs and then ringing his feeding bell and he still doesn’t try to attack them. He just sits there and watches me. Typically I feed frozen krill but I am planning on buying some small frozen clams to vary his diet. Other than predation I also didn’t think a fish would work because I was told mantis shrimps are messy eaters so I assumed it would be too much bioload to have a small fish and mantis in a 9 gallon but my mantis has been the exact opposite. He is a very clean eater. When I give him krill he grabs it and then slowly eats the soft meaty inner portion of the krill. Once he finishes eating he leaves his lair and brings the outside empty shell of the krill for me to take out of the tank to dispose of. Is there any fish suitable for this tank? I’m currently considering a single red firefish since I’ve heard of people keeping them in 10 gallons but I’m open to suggestions and advice and I’m not in a rush to get a fish, just curious as to what may work.

Mr. Mojo Rising · Jul 2, 2026

Personally I would not, 9 gallons is too small for most fish, definately too small for a firefish. Most fishes also sleep in the rocks which is where they get caught by the mantis at night. The tank is too small to avoid each other.

BryanM · Jul 2, 2026

I have one mantis left to catch in my tank, unwanted hitchhiker.

I believe he MAY be responsible for my couple of random fish deaths.

n.wennerae · Jul 2, 2026

Mr. Mojo Rising said:
Personally I would not, 9 gallons is too small for most fish, definately too small for a firefish. Most fishes also sleep in the rocks which is where they get caught by the mantis at night. The tank is too small to avoid each other.

The sleeping thing is another reason why I initially didn’t look into getting a fish but I’ve noticed my mantis is never active during the night and evening.