Sexy Shrimp Care: Thor amboinensis

With a stunning, almost 3-D appearance, you’d think sexy shrimp would stand out in a crowd. And when you DO see them, they’re an instant hit. The orange background serves as the perfect setting for blue-trimmed white spots. Taken together, it’s a striking look. Throw in those big, protruding eyes on short stalks? Yeah, too adorable for words.

Unlike other shrimp, sexies sport upturned abdomens and tails that curl back towards their heads. This leaves their legs free for dancing – a behavior they’re FAMOUS for. It’s also where the “sexy” part of the name comes in. With legs on constant display, they serve as the divas of the crustacean world. (Really, though, with “Thor” in their scientific name, could you expect anything less?)

However, plenty of people overlook these cuties. Sexy shrimp don’t grow much beyond 1¼ inches (3.2cm). Even with a vivid color palette, that allows them to slide under the radar. And since they develop commensulate relationships with sea anemones, it makes them harder to spot out on the reef. Hiding out within the protection of stinging tentacles, sexies clean the anemones. It’s an excellent symbiotic partnership. Of course, some sexy shrimp decide to nip at the anemone’s protective mucus – or even the ends of the tentacles. But when you’re THAT bitty? A few nibbles here and there won’t cause significant damage.

Sexies aren’t picky about the anemone they pair up with. Scientists and divers have spotted them climbing in, on, and around all of the following:

Sexy Shrimp Lifespan

Sexy shrimp circle the globe in the tropical regions. As long as they have a suitable sea anemone to partner with, they’re happy. Of course, divers and snorkelers need a keen eye to spot them among the tentacles of that anemone – even with those 3-D spots. The groups of shrimp don’t stand out the way you’d think. Well, not to humans, anyway.

To other invertebrates and fish, though, they’re hard to miss. Good thing sexies are one of the fastest crustaceans around. They can “sprint” for short distances at an impressive speed of 4-6 inches/second (10-15cm/second). That’s assuming a predator isn’t deterred by their dancing, of course. (We’ll cover that in a minute)

Combine that speed and a natural camouflage (not to mention the protection of the sea anemone’s sting), and sexy shrimp survive for around 3-5 years in the wild. In a captive environment, the average comes out closer to three years. This is usually due to management issues. But if you’re tops in your care, you may see longer.

Sexies are happy in water depths between 6-80 feet (2-25m). They form groups that cluster around their chosen anemone during the day. They’ll stay “close to home” while the sun’s out, sometimes venturing as close as the oral disk in their cleaning duties. Once the sun goes down (and the anemone retracts those stinging tentacles), sexies move away to another hiding place.

Despite what you’re probably thinking, you DON’T need to add a sea anemone to your tank if you want to keep sexy shrimp. While they appreciate it, these invertebrates adapt to their surroundings. And that means happily accepting alternatives of live rock and coral. Hiding places – such as the natural caves and crevices of a live rock structure – are the key.

Sexy shrimp remain active AND visible during the day. It’s one of the reasons aquarists love them so much. But they need somewhere to retreat to in the evening hours. Those adorable little crustacean bodies are hard for some fish to resist. And when you’ve danced the day away? You need somewhere safe to recover at night. If you don’t want the hassle of managing sea anemones, go for interesting contours of rock your sexies can explore.

Sexy Shrimp Tank Size

Given that precious minuscule size, sexy shrimp are a species ideal for pico or nano tanks. You can easily keep a group of 3-5 in a 5-gallon (19L) tank. (Incidentally, you WANT to keep a group. We’ll address why in a second) Of course, the smaller your tank, the more difficult the task of managing your water quality. So there’s a bit of a trade-off there.

Are Sexy Shrimp Reef-Safe?

Sexy shrimp pair off with sea anemones. And while the odd shrimp may decide to take a nibble at a tentacle on occasion, they can’t do much damage. Even a group’s grazing won’t cripple the anemone. And you’d assume the same would apply if you placed your sexies into your reef tank, right?

In theory. Sexies don’t have a problem switching hosts to corals. The polyps of Duncan’s coral, green stars, clove corals, and mushrooms work as a nice compromise. And the colonies don’t seem to mind the presence of dancing shrimp. The problem arises when your sexy shrimp don’t receive enough proper food in their diet.

When hungry, sexies fall back on their tentacle-chewing habit. The corals then retract their polyps in defense. This leads to a reduction in photosynthesis by the zooxanthellae. And (in extreme cases), the coral may begin to die. As long as you DON’T allow your sexy shrimp to scavenge for food on their own, though, this shouldn’t turn into a problem.

Sexy Shrimp Diet

Instead, you’ll want to provide supplemental foods. Commercial sinking pellets work fine, but you want to include some algae (nori works as a substitute) and protein in the mix. To prevent tank mates from stealing the bounty, target-feeding with a pipette works when you use these options:

When you’re ready to stimulate breeding? Choose food items with higher fat contents. Prepare for the excess waste in your tank, though. You’ll want to step up your water changes or increase the setting on your protein skimmer.

Sexy Shrimp Behavior and Tank Mates

Where’d that “sexy shrimp” name come from? If you spot a group of these crustaceans together, you’ll understand. To communicate (as a warning of an approaching threat or an attempt to dissuade a predator), sexies wave that up-curved hind end in the air as if they just don’t care. And the more sexies in a group? The more often they dance (the YouTube video below only shows one, but image MORE sexy shrimp strutting their stuff!).

Plenty of crustaceans prefer a solo existence. But sexy shrimp find low numbers stressful. “The more, the merrier” applies to this species. You don’t want to go below three for a group, or your sexies will attempt to hide out. It’s the group dynamic that eases that stress level and promotes activity.

And while these delightful little dancers attract attention, it doesn’t mean you’re limited to that pico tank on your office desk. If you introduce sexies to the tank FIRST, you can set up a nano display with other species that will get along in perfect harmony:

Other fish you’ll need to avoid include:

Breeding Sexy Shrimp

The majority of sexy shrimp come wild-caught. Since the species IS global in distribution (and not difficult to find), people haven’t rushed to set up captive breeding operations. Not to mention that breeding this particular crustacean is labor-intensive. It doesn’t mean you should write it off, but make sure you’re ready for the effort involved.

Sexy shrimp are protandric hermaphrodites. This means all shrimp are born male and switch to female when they reach an appropriate size (and with the right social cues). As such, females are the larger – and wider – of the two. The extra width allows them to carry the eggs. You’ll also see a “broken stripe” along the back and tail.

If you want to breed sexies, you’ll need a separate tank to raise the larvae. Without it, the more the tiny sexy shrimp end up eaten. (Yes, even if you have a single species tank) If you have the resources, a cylindrical recirculating tank works best. The shape allows the current to direct larvae AWAY from the glass walls. (They’re not strong enough to pull themselves away, and then you get squished shrimp which aren’t very sexy)

You’ll want the same water conditions but leave out all of the rock and substrate. All you need is a heater and an air stone (and don’t go overboard on the setting; all you want is gentle water movement).

Sexy shrimp lay anywhere between 100-300 eggs at a time. And you can encourage spawning with those high-fat foods. Eggs hatch within 2-3 weeks, usually in the evening. You’ll know it’s close to time because they’ll turn a dark brown color. To collect the larvae (and prevent them from becoming delicious snacks), add a light to one side of the tank. They’ll move toward it, allowing you to GENTLY siphon them up and transfer them into the rearing setup.

You don’t want more than 40 larvae per 2.5 gallons (10L). Any more, and you’ll end up with too much waste to cope with. Considering you need to perform 30-50% water changes TWICE a day as it is, cleanliness tops the list of importance.

Sexy shrimp undergo eight larval stages before they molt into a final decapod and settle. The development takes 26-28 days, with another 10-12 days before they emerge as their sexy selves. It means plenty of work for you. And it’s why no one’s embarking on commercial breeding operations. Not when collecting adults requires less time and effort.

Pros and Cons

Once you see a sexy shrimp group go into a dance, they’re hard to resist. And since they’re not difficult to care for, you’re probably planning your next nano or pico tank in your head. But every species comes with little quirks, and it’s important to look at every aspect before you make that purchase.

Pros

• Unlike some crustaceans, sexy shrimp prefer to stick in groups – and the larger the numbers, the lower the stress level.
• While sexies share a symbiotic relationship with sea anemones in the wild, you don’t need to keep an anemone in the tank; they’ll adapt to live rock or coral without a problem.
• Sexy shrimp don’t require specialized diets, accepting anything from commercial sinking pellets to nori to meaty proteins.

Cons

• While hardy, sexy shrimp don’t tolerate changes in water conditions, making it difficult to acclimate them when first bringing the invertebrates home.
• If not fed well or adequately, sexies CAN start to graze on coral polyps.
• Sexy shrimp will breed in captivity, but raising the fry is labor-intensive and complicated, making it easier to collect them from the wild.

Finding a species of shrimp that’s active and visible during the day isn’t an easy task. It’s one reason hobbyists LOVE sexy shrimp. And if that isn’t enough for you (or, you know, getting to see how many times you can say “sexy” in one conversation before someone wonders what you’re talking about), you can always find some extra tidbits of information here.

This YouTube video breaks down everything you could want to know about sexy shrimp:

Want to know about some of the best sexy shrimp tank mates?

Or maybe you’re interested in learning about the corals you can use as substitutes for anemones:

Conclusions

Are sexy shrimp charming and enchanting – a little like the god of thunder they share a name with? Perhaps that’s a matter of opinion. No one can doubt they catch the eye, though. And everyone stops to watch impromptu dance parties. It makes these crustaceans the perfect addition for anyone who enjoys an active, vibrant aquarium. (Or loves making videos they can set to music)

References