The first time I spotted a Urocaridella shrimp was on a toasty Thai reef. I was hovering above a group of highly photogenic camel shrimp, snapping away on my camera, when I noticed one of them was not like the others… at all. It hovered a few inches above the substrate and sported a mostly translucent body with subtle red and white accents, plus long, candy cane-striped arms. I’d never seen a juvenile coral banded shrimp (Stenopus hispidus) before, and assumed that was what it was—the colors and arms fit perfectly. 

As usual when trying to guess at an ID, I was wrong. I’d actually met Urocaridella antonbruuni, one of the rarest shrimp in the aquarium hobby.

Meet the Urocaridella

I appreciate a good Lysmata cleaner shrimp as much as the next gal, but microshrimp (if that wasn’t a word before, it is now) are really where it’s at for me. No squabbles and no sneaking bites from my corals, just peacefully foraging Thor, Periclimenes, Ancylomenes, and, of course, Urocaridella. With their maximum body length of 2” and weight of just half a gram for adults—yes, researchers have weighed them—these tiny crustaceans are right up any nano reefer’s alley.

You’ll usually see these small Palaemonids labeled as “arrow cleaner shrimp”, but I personally think “hover shrimp” would be much more descriptive: they rarely seem to touch the reef floor. I’ve seen them described as reminiscent of mosquitoes due to their hovering swimming style and long, trailing chelae. This movement pattern, combined with their mostly transparent bodies dotted with blocks of color, makes them instantly recognizable. True, Ancylomenes can look similar, but those usually sport at least some purple, which Urocaridella lacks entirely (plus, hover shrimp aren’t associated with anemones at all).

There are currently eight recognized species of arrow cleaner/hover shrimp, the most recent described in 2020 from India: U. arabianensis, which locals immediately recognized as valuable for the aquarium trade. Sadly, it looks like breeding efforts haven’t worked out for this species, nor any of its cousins, and Urocaridella shrimp are still quite obscure both in the aquarium hobby and scientific circles. They mostly pop up as hitchhikers, but aren’t usually targeted specifically due to apparently being challenging to ship. Maybe if we all ask for them at our LFS, collectors will refine their protocols for lower mortality… maybe.

Buyers report Urocaridella antonbruuni, U. degravei, and varied mystery customers in shipments from collectors targeting caves or overhangs in Indonesia and the Philippines. The many “Sp.” and “Spp.” may be local color morphs or as yet undescribed species—I think we’ll be seeing more Urocaridella described in years to come. There’s a variety with abundant red spotting that I’d particularly like to see named!

Can you see why I thought this mystery customer must be a juvenile coral banded shrimp?

Aquarium set-up

Urocaridella are typical reef shrimp (and fully reef safe!). They’ll do well in most types of systems, their only specific requirements being the availability of a few caves or overhangs and a low flow level—their hovering indicates they’re not used to being blown around the water column. Experienced nano reefers can try a few in a tank of 5 gallons or up, although 8+ does provide them more room to hover and allows you to keep a larger group.

Standard reef parameters will work fine for hover shrimp. Choose tankmates with care: although cleaner species are mostly left alone in the wild, that context is missing in the aquarium, causing small shrimp like these to end up as snacks. Your best bet is an invertebrate-only set-up, but you can also consider small reef species like clowns or chromis. Do make sure there are plenty of hiding places available, as hover shrimp are known to be particularly skittish and might succumb to stress without caves to dart into.

Diet

Like many of our favorite aquarium shrimp, Urocaridella are diligent cleaners. Studies have revealed many work day and night, alone or in small groups, cleaning anything from morays to angelfish. Like some other cleaners, they advertise their services through a rocking dance, but the addition of a hovering swimming style is unique and might help to outcompete perching cleaner species like Periclimenes.

You might spot your Urocaridella shrimp cleaning fish in your aquarium, but they’ll need supplemental feedings to thrive. Given their status as opportunistic omnivores, anything goes: try sinking pellets, flakes, frozen food, algae tablets, gel food, chopped seafood, or whatever else you have on hand. You don’t have to target the shrimp specifically unless you think they’re not getting enough.

Conclusion

The tiny, hovering Urocaridella may be the most underappreciated shrimp in the aquarium hobby. Let’s keep our fingers crossed for importers to catch on soon!

Sources & further reading

Akash, S., Purushothaman, P., Madhavan, M., Ravi, C., Hisham, T. J., Sudhakar, M., … & Kuldeep, L. K. (2020). Urocaridella arabianensis n. sp., a new Palaemonid shrimp (Crustacea, Decapoda, Palaemonidae) from Lakshadweep Islands, India with taxonomic comparison on the genus Urocaridella Borradaile, 1915. Zootaxa, 4816(1), zootaxa-4816.

Becker, J. H., Curtis, L. M., & Grutter, A. S. (2005). Cleaner shrimp use a rocking dance to advertise cleaning service to clients. Current Biology, 15(8), 760-764.

Bharathi, S., Jayakumar, T. T., Kumar, T. A., & Lal, K. K. (2023). Embryonic development of the ornamental shrimp, Urocaridella arabianensis Akash et al., 2020. Indian Journal of Geo-Marine Sciences (IJMS), 52(08), 402-406.

Cryan, D. M., Vaughn, K. M., & Caves, E. M. (2024). Nocturnal Cleaning Interactions Between the Giant Moray (Gymnothorax javanicus) and the Clear Cleaner Shrimp (Urocaridella antonbruunii). Ecology and Evolution, 14(12), e70589.

Prakash, S., & Baeza, J. A. (2018). A new species of shrimp of the genus Urocaridella Borradaile, 1915 (Decapoda: Caridea: Palaemonidae) from Papua New Guinea. Journal of Crustacean Biology, 38(2), 206-214.