Keeping and caring for filter-feeding shrimps.
Filter-feeding shrimp is a name that has recently established itself in aquarium hobby for these creatures, whose popularity is growing day by day. Various representatives of the vast family Atyidae, which unites shrimps, live mainly in subtropical and tropical countries. In English-language aquarium literature, filter-feeding shrimps are called “Fan shrimps”.
Currently, representatives of two genera of filter-feeding shrimps can be found for sale: Atyopsis and Atya. Usually, all shrimps from the genus Atyopsis are referred to as the species A. moluccensis, but most likely here we are dealing with several close and difficult-to-distinguish species. Strictly speaking, Atyopsis moluccensis inhabits the Moluccas. However, very similar shrimps live on numerous islands in the vast region from the Philippines to New Zealand, as well as directly in continental Southeast Asia. In fact, we do not know the exact origin of the shrimps that end up in Russia by the will of fate. Whether they can all be attributed to a single species is unclear, so for now, when talking about these shrimps, it is more correct to limit ourselves only to the generic name: Atyopsis.
In the pet trade, shrimps of the genus Atyopsis are often called “Banana shrimp”. In addition, in English-language sources, these filter-feeding shrimps are also called Wood shrimp, Singapore shrimp, Rock shrimp. Apart from these, one can occasionally encounter various other and equally strange names.
Filter-feeding shrimps are not small creatures. They are heavy and clumsy. Why? The fact is that their fans, although a very perfect creation of nature, still offer resistance to the water current, so a significant body mass is needed to firmly direct them against the current without the shrimp itself being washed away by the flow. In addition, the limbs of the sixth thoracic segment (the first pair of walking legs) are transformed into powerful “hooks” that hold the animal in the current. As a result, these creatures have to walk using only two pairs of legs, which is quite difficult.
They have two pairs of thoracic legs transformed into catching fans, or little brooms, with the help of which they earn their daily bread. In essence, the fan is still the same claw that terminates the limbs of certain thoracic body segments in filter-feeding shrimps. In filter-feeding shrimps, the fans adorn the limbs of the 4th and 5th thoracic segments (the first three thoracic segments bear maxillipeds, and segments 6–8 bear walking legs).
The fan consists of two hemispheres formed by a dense row of resilient setae. Now food comes right into these shrimps’ hands: one just needs to choose a suitable feeding spot in the current. In all likelihood, these magical transformations began with the fact that it became profitable for shrimps to learn how to sweep the bottom of a water body well. Fans, which are very convenient for collecting food particles, provide incomparably greater productivity.
In filter-feeding shrimps, the “claws” have become much more graceful, the penultimate segment of the limb (the base of the claw) has significantly changed its shape, elongating transversely so that the fan can open wider, and abundant long and resilient setae have appeared at the ends of the claw’s processes. Some of the setae forming the fan have hooks at the ends that prevent the collected goodies from slipping out of the trap at the moment it snaps shut. Indeed, river waters carry a mass of suspended particles, including quite edible ones.
Filter-feeding shrimps cannot be called bottom-dwelling animals. They master the entire space of the aquarium and can take positions near the water surface on grottoes, driftwood, and aquarium equipment. So that the filter feeder can constantly sit, so to speak, in the water flow, it is advisable to put some driftwood, a stone, or any other object on the bottom of the aquarium. If this shrimp does not have the opportunity to settle in the path of the water flow, it will try to move closer to the filter, often climb into the filter tubes, and may even crawl out of the aquarium. Sometimes they perform good acrobatic stunts that can end in escaping from the aquarium. Therefore, do not forget to cover the tank with shrimps. If you see a filter feeder sitting on top of the aquarium or somewhere right at the very top, this is the first signal for you that it has no feeding conditions.
The shrimps are positioned in the current, head against the flow, and open their fans, which gradually fill with food by themselves. The owners of such a useful device in shrimp life 
only need not to miss their mouth. Periodically, the trap-fan snaps shut and is pushed into the mouth. Interestingly, each hemisphere folds independently of the other. The shrimp cleans the fan from food particles very quickly and skillfully, while the setae folded into a tight bundle almost completely disappear among the numerous jaws and maxillipeds. Young shrimps lead a rather secretive lifestyle and sit to filter under some shelter, particularly under a leaf. This is a favorite position that can remain unchanged for weeks. The shrimp will become bolder as it grows up.
For a happy life, Atyopsis needs a current. Arrange a place for it somewhere opposite the filter outlet. Stick sticks directly into the stream from the filter and attach a few suction cups to the glass, thus forming protrusions on it. Direct the filter outlet toward this glass. All shrimps will eagerly climb onto the sticks or catch onto the suction cups on the glass. As long as there is a current there, you won’t drive them away with a broom. If the current weakens (the filter is clogged, electricity is turned off), it sets off in search of other current sources, for example, bubbles from an air pump.
As long as there is a current, it will not walk around your aquarium. It may only try to change position in search of a more comfortable posture for letting water through itself. Therefore, we can say that the filter-feeding shrimp is the most boring inhabitant. For this reason, any peaceful aquatic animals can be kept with this shrimp: from newborn guppies to cherry shrimps.
Shrimps need to be fed, as aquarium water is quite poor in plankton. You can feed them by spraying any dry foods or their mixture in the current, as well as small frozen bloodworms. An important point in keeping Atyopsis, oddly enough, is the presence of a certain amount of suspension in the water. I don’t mean “turbidity”, or that the water should be cloudy. It’s just that in crystal clear water, Atyopsis will inevitably starve. Shrimps must have the opportunity to constantly catch at least something in the water. Clay will also contribute to the development of the shrimp’s chitinous shell.
Shrimps should be fed with high-quality dry foods for aquarium fish. In particular, very small, slowly sinking granules for feeding fry are suitable. It must be borne in mind that small food floating in the water column of the aquarium for a long time can greatly spoil the water, so if there is no suitable food of proper quality, it is better to feed these shrimps with bloodworms and catfish tablets, simply throwing them to the bottom. Filter-feeding shrimps cope with such food perfectly. Frozen daphnia and cyclops, as well as live Artemia nauplii, are also suitable for them. Shrimps can perfectly collect food that has settled to the bottom using the “sweeping” method.
Sometimes a situation arises when there is no suspended food in the water and none is expected, but the shrimps stubbornly refuse to work their brooms. They stubbornly sit in the strong current near the pump and, having waited for nothing, can even die of hunger. In this case, you need to turn off the pump before feeding. When the current in the aquarium disappears, the shrimps will understand that food will not swim to them by itself, and will start sweeping the bottom.
Large male filter-feeding shrimps are very impressive creatures. It is clear that the walking legs of the sixth thoracic segment are unsuitable for walking and are rather powerful hooks that hold the animal in the current. In representatives of the species Atya gabonensis, females, unlike females from another genus of filter-feeding shrimps, Atyopsis, possess powerful front hook-legs just like males. They also have swimming legs (pleopods) on the abdominal segments and a powerful “tail fin” formed by the last body segment (telson) and flattened lobe-legs of the sixth abdominal body segment (uropods).
With their help, filter-feeding shrimps can swim quite well. Moreover, both forward and backward. Usually, shrimps swim head first, but they are also well-versed in the crayfish escape method, which they use when they get into an extreme situation. By sharply bending the abdomen with widely spread lobes, they can make a swift backward dash.
It should be noted that molting is a serious test even for adult shrimps, but if the aquarium conditions are suitable for them, it ends successfully in 
most cases. They literally crawl out of their skin, and doing this is not easy. Moreover, during molting, shrimps regenerate lost body parts. Therefore, you can take a risk and buy a shrimp with an incomplete set of legs or antennae, and such specimens are often found for sale, because all of them came to us from distant warm countries and experienced many hardships during quarantine at importing firms. Create good living conditions for such a shrimp, and within a few months, the lost body parts will regenerate.
The conditions suitable for the life of all filter-feeding shrimps are approximately the same. The water should have a neutral or slightly alkaline reaction (pH about 7 or higher). It is desirable that the water hardness be at least 6–8 GH, although keeping these shrimps in softer and even slightly acidic water is possible. Aeration, filtration, and a noticeable current are necessary in the aquarium. Ammonia and nitrites should not be present in the water of the aquarium with shrimps; in addition, it is desirable to maintain as low a nitrate level as possible — in any case, it should not exceed 40–50 mg/l. Water temperature can range from 24–28 °C. When the temperature drops below 22 °C, the shrimps clearly feel bad.
Unfortunately, there are still no reports of successful home breeding of any species of filter-feeding shrimps. Females attach several hundred small eggs (about 1.8 mm in diameter) to their pleopods and carry them for about 22 days. Swimming larvae hatch from the eggs, which soon die during molting or are successfully filtered out and eaten by the parents if the offspring are not removed in time. Probably, they can develop successfully only in marine or brackish water and need some specific food.
Atyopsis moluccensis, Banana shrimp.
Euryrhynchus amazoniensis, Halocaridina rubra, Xiphocaris elongata. 
