‘Sexy’ Shrimp – Detailed Guide: Care, Diet, and Breeding

The ‘Sexy’ Shrimp (Thor amboinensis) enjoy a level of popularity in the aquarium hobby that borders on fanaticism. This is one of the most strange, beautiful and recognizable species of shrimp that you can keep in a marine tank. The combination of spectacular colors, cleaning functions and relatively simple care places them between one of the most preferred ornamental species of marine invertebrates.

Some aquarists believe that the successful care of the Sexy Shrimp depends on anemones … Well, this is not exactly so. Even more, in some cases (like breeding), it will be better to keep them away from any anemones. 

In this article, I will discuss the optimal conditions for keeping the ‘Sexy’ Shrimp, their behavior, diet, reproduction and much more.

Quick Notes about ‘Sexy’ Shrimp

Name	‘Sexy’ Shrimp
Other Names	Sexy anemone shrimp, Anemone shrimp, Squat shrimp, Humback shrimp, High-tailed shrimp, Pikmin shrimp and Dancing shrimp
Scientific Name	Thor amboinensis
Tank size (minimum)	5 gallons (~20 liters)
Keeping	Easy
Breeding	Difficult
Size	up to 2 cm (~0.8 inches)
Optimal Temperature	24 – 27°C  (~75°F – 79°F)
Water type	SG = 1.023 – 1.025
Optimal PH	8.1 – 8.4
Optimal KH	7 – 12
Nitrate	Less than 20 ppm
Diet	Carnivore
Temperament	Peaceful
Life span	up to 3 years
Color Form	Orange coloration with number of large white spots outlined in blue

Natural Habitat of the ‘Sexy’ Shrimp

The ‘Sexy’ Shrimp is a circumtropical symbiotic species found on coral reefs in a depth range of at least 2 to 25m in all tropical oceans. Where they usually found living within the tentacles of various sea anemones. Occasionally, Thor amboinensis can be found free-living in dead corals, small cracks in rocks, and in biogenic gravels.

Thor amboinensis is currently ranging from the Red Sea through the Indo-Pacific, Caribbean, and Atlantic terminating at the Canary Islands off the coast of Africa.

Western Atlantic: Bahamas, southern Florida, Caribbean Sea, Brazil.
Eastern Atlantic: Madeira, Canary Islands, Cape Verde Islands.
Indo-West Pacific: Kenya, Madagascar, Bay of Bengal, Andaman and Nicobar Islands, Japan, Taiwan,
Philippines, Indonesia, Palau Islands, Caroline Islands, Marshall Islands, Australia).
Eastern Pacific: Costa Rica (Cocos Islands), Panama (Pearl Islands), Ecuador, Chile (Easter Island).

Description of the ‘Sexy’ Shrimp

Thor amboinensis commonly known as the ‘Sexy’ Shrimp in reference to its usually raised tail and to the curious body movements when walking swaying its abdomen back and forward with exotic elegance, this fascinating behavior, as well as their beautiful colors, contribute to its popularity in the ornamental trade.

The ‘Sexy’ Shrimp are small shrimp. They are usually less than 2 cm in size. Females are bigger than males, for example, males usually grow only up to 1.5 cm (0.6 inches) long.

They have short-stalked eyes that are protruding from their carapace. The rostrum is well developed and does not overreach the eyes or expand ventrally.

The ‘Sexy’ Shrimp have a distinctive orange coloration with the number of large white spots outlined in blue. The abdomens and tails of these shrimp arch upwardly towards their heads.

Once a proper aquarium is set up and optimum living conditions are met, ‘Sexy’ Shrimp can grow, reproduce and live up to 3 years.

The Behavior of the ‘Sexy’ Shrimp

The ‘Sexy’ Shrimp are extremely interesting in terms of behavior. As I have already mentioned, the common name is coming from its unusual dance, which involves holding its abdomen up in the air and waving it up and down. They do their dance almost all the time.

They are completely peaceful creatures and usually do not bother anybody in the tank.

The ‘Sexy’ Shrimp are also very social and tend to aggregate in large groups potentially reflecting the small size and limited defensive capability of these shrimps.

They will often share a hiding place, it is not uncommon to see many of them in the same areas. In the group, they feel more relaxed and confident. At the same time, they lack social structure.

‘Sexy’ Shrimp can move very quickly and are capable of going short distances 15 – 20 cm (6 – 8 inches) in the blink of an eye.

This species is usually associated with corals and anemones, however, in aquariums ‘Sexy’ Shrimp can also live free without any anemones.

‘Sexy’ Shrimp and Anemone Partnership

According to the studies, Thor amboinensis has been encountered in association with at least 12 different genera of sea anemones, for example:

• Telmatactis cricoides,
• Stichodactyla spp.,
• Cryptodendrum adhaesivum,
• Macrodactyla doreensis,
• Phymanthus sp.,
• Heteractis spp.,
• Actinodendron plumosum,
• Cryptodendrum adhaesivum,
• Anemonia sulcate,
• Zoanthus sp.,
• Lebrunia danae,
• Entacmaea Quadricolor,

Symbioses are common in the marine environment. Some taxa appear to be particularly likely to be involved in associations. It is the crustaceans that probably form more associations with other classes than any other marine animals.

The ‘Sexy’ Shrimp that associate with habitat providers (or ‘hosts’) may obtain a variety of benefits, including physical shelter from predation, camouflage, stability, range expansion, or advantageous positioning. In return, they clean anemones.

Most often, they consume planktonic organisms that get caught by the anemone’s tentacle. Contact between the shrimp and the tentacles do not elicit feeding reactions of the anemone. The tentacles do not cling to the shrimp and the shrimp showed no signs of being stung.

During daytime, the ‘Sexy’ Shrimp can be found on the substrate in the immediate vicinity of the tentacles of the anemone, on the column of the anemone and occasionally even on the tentacles and on the oral disk of the anemone. Whereas during nighttime, when the anemone contracted its tentacles, the shrimp usually move either to the column or away from the anemone.

It is interesting but Thor amboinensis was observed sharing the same host with other shrimps and even the spider crab Mithrax sp. Groups usually contained adult and much smaller individuals. Another interesting fact is that ‘Sexy’ Shrimp are attracted to its host anemone mainly by chemical signals.

Read also my article “Proper Care for Carpet Anemones”.

Are the ‘Sexy’ Shrimp Reef Safe?

Yes, in most cases you will not have any problems with ‘Sexy’ shrimp in reef tanks. However, even amongst the orderly tenants, there is always a chance that some individuals will go in “Rogue mode” and start picking up corals. Some aquarists say that they can eat SPS frags and destroy polyps.

Just be careful and watch them closely in the beginning.

Feeding ‘Sexy’ Shrimp

Feeding is easy. Sexy Shrimp is a carnivore species. They will accept a wide range of fish, shrimp or sea anemones food. No direct feeding is necessary, as they can also feed off the slime of corals in the aquarium. At the same time, they eat trapped organisms within it that they feed upon.

In case your tank does not have any anemones, they will require some food. The problem is that too often Sexy Shrimp are viewed as simple scavengers, with the idea that they can survive off the leftovers from feeding community fishes. This is problematic for two reasons.

First, if there is leftover food in the tank, it means that you are overfeeding the tank in the first place. Therefore, adding something that will supposedly clean it is not the solution. The solution is to feed less. Second, they should not be treated just as the aquarium janitors.

They will do best when fed a sinking food. Any pellet, flake, and gel foods that provide animal-based nutrition will work. Meaty food with higher fat content can accelerate breeding, but the trade-off is risking a problem with water quality.

Many quality frozen foods also sink and can provide an excellent diet, especially if you are attempting to breed Sexy shrimp.

Caring and Keeping ‘Sexy’ Shrimp

Keeping Sexy shrimp in an aquarium is not complicated because they do not have special water quality requirements. Basically, they should be maintained under conditions that suitable for any other typical reef-aquarium inhabitants.

The salinity should be in the range of 1.023 – 1.025 as measured using its specific gravity.

The temperature should stay in the range of about 72 to 82 F (22 to 28 C) with around 75 to 79 (24 – 27C) being optimal. Iodine is also believed by many to be an important factor for the molting process. Therefore, use an iodine additive per the maker’s instruction.

The concentration of calcium, the PH and the alkalinity of the aquarium’s water must be maintained at acceptable levels as well. Keeping calcium concentration in the range of 400 to 450 ppm is optimal, but they can be a bit lower or higher. The pH should be kept around 8.1 to 8.4 and alkalinity should be kept in the range of 7 to 12 dKH, although these often go a little higher or lower.

Tank décor should include plenty of structures for the shrimp to hide, especially when they are young.

If the conditions are met, this shrimp will delight you with its funny behavior and make periodic adventures from sea anemones.

Do not forget that they need careful acclimation (read more about it here) as all invertebrates. Do it very slowly. In general 2 – 3 hours will be good enough. Sexy shrimp do not like swings in salinity. 

Basic Tank Equipment (links to check the price on Amazon) Filter:   Marineland Penguin Power Aquarium pump: Tetra whisper Air pump Heater:  Tetra HT Submersible Substrate:  Nature’s Ocean Live Rock:  Carib Sea Sea Salt: Instant ocean marine salt. Test Kits: API Aquarium Water Test Kit Aquarium Hydrometer: Salinity Refractometer for Seawater and Marine Fishkeeping Aquarium 0-100

Sexing ‘Sexy’ Shrimp

There are many people who have some problems with sexing ‘Sexy’ Shrimp. Actually, it is not somewhat difficult to even for the untrained eye. There are few indicators that give away the sex of the shrimp. 

1. The larger Sexy Shrimp are females. Males are smaller.
2. In the absolute majority cases, in females Sexy Shrimp, the white stripe across the back is broken. The males do not have broken stripes, it just looks like a single dot/stripe.
3. Due to the fact that females carry eggs, the underside (abdomen) of the females is wider, it goes down to protect the eggs. Males Sexy shrimp are thinner.

Breeding ‘Sexy’ Shrimp

Breeding Sexy Shrimp is tricky and difficult. The few existing larval descriptions and the lack of knowledge on the larval morphology and development of the species of Thor are two of the bottlenecks that are impairing the captivity production of this shrimp species.

There are not many aquarists in the world who can systematically and successfully do that. Luckily, some of them share this precious information, so more people can breed ’Sexy’ Shrimp in captivity. The role of captive breeding could help to reduce the number of ‘Sexy’ Shrimp collected from the wild. Therefore, I would like to say Big Thanks to Russian reef keeper zubo4istka and American guy iretthepirate. All credits go to them.

To save you some time, I have combined their experience with some scientific studies and this is what we have.

Some Facts about Breeding ‘Sexy’ Shrimp

1. Thor amboinensis is a protandric hermaphrodite that first matures as male, changing to female later in life. Once they reach 15 – 18 mm (0.6 – 0.7 inches), they usually become female.
2. They can produce several hundred eggs (100 – 300) during each spawn.  Clutch size increases approximately exponentially with increasing female size from that point.
3. Larvae typically hatch within 14 – 20 days of fertilization. After spawning, as the larvae develop, the eggs in the egg mass progress from yellow color towards transparency.

1. Thor amboinensis embryos hatch as planktonic larvae termed zoeae.
2. The number of stages a larva undergoes prior to settling is 8 and one decapodid.
3. Larval duration period ranges from 26 – 28 days. Complete transformation can take another 10 – 12 days.

Rearing ‘Sexy’ Shrimp Larvae Set Up

1. The rearing setup requires the same water parameters.
2. Do not use any substrate, rocks or decorations – just a bare bottom with the heater and airstone. Be very careful with airstone, the flow should constantly move larvae but not fast.
3. Do not use sea anemones in rearing set ups. According to the study, in laboratory conditions, the sea anemone  consumed larvae of Thor amboinensis.

1. In captivity, larval food quality and quantity, amiss stocking densities have shown to be important factors determining larval survival of ornamental marine shrimp.

5. You should separate larvae from the main tank. Ideally, you need to use cylindrico-conical recirculation tanks. Its shape provides the best circulation and prevents larvae to touch the glass walls. If they tough the wall, they cannot separate themselves anymore and die.

1. Stock at a density of about 40 larvae in 10-liter (2.5 gallon) tanks.

7. Do (30 – 50 %) water changes 2 times a day (morning and night).
8. Diet is extremely important! You need to feed them freshly hatched baby brine shrimp (at a density of 10,000 nauplii L-1) 2 times a day or they die. Note: they only eat the yolk sac on brine shrimp, which lasts only 12 hours. 

Under laboratory conditions, the molt to decapodid occurred 28 days after hatching.

First zoea (size) = 1.99–2.30 mm;
Second zoea (size) = 2.16–2.50 mm
Third zoea (size) = 2.52–2.74 mm;
Fourth zoea (size) = 2.98–3.38 mm;
Fifth zoea (size) = 3.35–3.85 mm
Sixth zoea (size) = 3.62–3.85 mm
Seventh zoea (size) = 4.08–4.38 mm
Eighth zoea (size) = 4.31–4.61 mm;
Decapodid (size) = 4.41–4.52 mm

‘Sexy’ Shrimp and Suitable Tankmates

The ideal situation for the Sexy shrimp is a species tank, but it can be kept with other fish as long as those species are chosen with care. Aggressive eaters should be avoided. Large predators such as triggerfishes, wrasses, hawkfishes, and angelfishes do not make suitable tankmates as well. Clownfish would be also unsuitable, as they would not want anybody in their anemone!

Sexy shrimp get along well with others of its kind, so maintaining a group is not problematic but it will require more space.

Boxer crabs, snails (Cerith Snails, Bumble Bee Snails, Conch snails, Nassarius snails, etc.), porcelain crabs, Emerald crabs, cleaner shrimp (Peppermint shrimp, Red Fire shrimp, Skunk Cleaner Shrimp, Red-white Cleaner Shrimp),Saron Shrimp, Bumble bee shrimp usually do not bother Sexy shrimp. There should not be any problem with Porcelain anemone crab which also need anemones. They do not compete for them. 

In Conclusion

‘Sexy’ shrimp is highly valued in the ornamental aquarium trade. They are not only beautiful shrimp but also stay on the smaller side – perfect for someone with limited space like nano reef tanks.

References:

1. Complete larval development of Thor amboinensis (De Man, 1888) Decapoda: Thoridae) described from laboratory-reared material and identified by DNA barcoding. Zootaxa 4066(4):399. January 2016. DOI: 10.11646/zootaxa.4066.4.3
2. Sarver, D. (1979) Larval culture of the shrimp Thor amboinensis (De Man, 1888) with reference to its symbiosis with the anemone Antheopsis papillosa (Kwietniwski, 1898). Crustaceana, 5 (Supplement), 176–178.
3. Baeza, J.A. & Piantoni, C. (2010) Sexual system, sex ratio, and group living in the shrimp Thor amboinensis (De Man): relevance to resource-monopolization and sex-allocation theories. The Biological Bulletin, 219, 151–165.
4. Calado, R., Narciso, L., Morais, S., Rhyne, A.L. & Lin, J. (2003b) A rearing system for the culture of ornamental decapod crustacean larvae. Aquaculture, 218, 329–339. http://dx.doi.org/10.1016/S0044-8486(02)00583-5
5. Three shrimps, five nudibranchs, and two tunicates new for the marine fauna of Madeira. December 1994
6. Crustacean symbionts of the sea anemone Telmatactis cricoides at Madeira and the Canary Islands*. Journal of Zoology 242(4):799 – 811. May 2009. DOI: 10.1111/j.1469-7998.1997.tb05827.x
7. Ectosymbionts of the sea anemone Stichodactyla gigantea at Kosrae, Micronesia. April 2016. DOI: 10.5635/ASED.2016.32.112
8. Hippolytidae and Barbouriidae (Decapoda: Caridea) collected during the Ryukyu “KUMEJIMA 2009” Expedition. Zootaxa. July 2012. DOI: 10.11646/zootaxa.3367.1.9
9. Ecological traits of Caribbean sea anemones and symbiotic crustaceans. Marine Ecology Progress Series. December 2012. DOI: 10.3354/meps10030
10. Spatial distribution of symbiotic shrimps (Periclimenes holthuisi, Pbrevicarpalis, Thor amboinensis) on the sea anemone Stichodactyla haddoni. Journal of the Marine Biological Association of the UK. February 2004. DOI: 10.1017/S0025315404009063h
11. Papéis Avulsos de Zoologia. Volume 57(14):157‑176, 2017. http://dx.doi.org/10.11606/0031-1049.2017.57.14