#candy shrimp

[ihavesweatypalms6]

Dies

I hope no one hates me for this art ahah

[deviouszebra]

Caridina babaulti

[aquariuminfobureau]

Most of the shrimp morphs favored by freshwater aquarium hobbyists, are Neocaridina sp. or other fan shrimps. However the South Asian species Macrobrachium agwi is very different. This is the striped 'prawn' or candy shrimp, or the dwarf or bumblebee large-armed shrimp, where 'large armed' is a translation of the genus name Macrobrachium. Before its formal description as a species, M. agwi was identified as a distinctive morph belonging to the genus, and traded as Macrobrachium sp. 'Banded'.

From the tips of their rostrums to the tips of their telsons, M. agwi are around 5 to 6 centimeters or 2 to 2 and a 1/3 inches long. The long claws are not included in this measurement, but they add significantly to the length of the animal, when they are in extended posture. Such a length is much smaller than that of some well known Macrobrachium species, and that is why M. agwi is sometimes traded with the name 'dwarf', although there are other small species among Macrobrachium.

M. agwi is a member of the successful and diverse genus Macrobrachium, to which a large number of species belong. Although it is customary to label Macrobrachium as prawns, many would argue that they are in actuality shrimps, although it is semantic. Also the genus Palaemon, although they are 'the' prawns on the British table, would also technically be shrimp using the same argument. In addition to their use in aquaria, a small number of Macrobrachium sp. are aqua cultured as food, primarily M. rosenbergi. Aquacultural interest in farming members of this genus has increased the knowledge base available for their aquarium care, though the focus is only on the large species that humans culture for food, not M. agwi.

When wild Macrobrachium sp. are exported for the aquarium trade, the exact species involved may be difficult to ascertain. Macrobrachium are mostly freshwater animals as adults, although some species in the genus are estuarine, and only one of these species is also faculatively marine. The planktonic larvae of a number of Macrobrachium species are exported out to sea downstream, therefore they possess tolerance of low salinity, before losing it, and later regaining the tolerance as late juveniles migrating upstream.

Many species of Macrobrachium thus require saltwater for their larval development, however M. agwi has abbreviated or direct development, and completes its entire life cycle in freshwater. M. agwi carries fewer and larger eggs than do some other freshwater Macrobrachium species, budgeting its energy into fewer offspring, with an abbreviated larval life after hatching. These larvae do not feed but continue to be sustained by the yolk donated by their mother. The development of their jointed appendages becomes accelerated, because these freshwater larvae are benthic and non-planktonic from the start.

In freshwater and some other environments, such a life history comes under positive selection, because the amount of plankton available as food for feeding larvae, is either consistently low, or is unpredictable. Such a life history has repeatedly evolved among the clade of shrimps, crabs, and lobsters. M. agwi and other fully 'freshwaterized' shrimp have broken completely with the habitat of their marine ancestors, and have also lost their physiological tolerance of saltwater at any of their life stages, because their ancestors had no further need to continue tolerating saline waters.

The species M. agwi was described from specimens collected at Barobisha, in the Alipurduar District of West Bengal but close to her border with Assam. The climate of Alipurduar is monsoon-influenced and shows variation over the year, from an air temperature of 14 degrees centigrade in the coolest month, to 34 degrees in the warmest month. The water of the Kaljani, the river of Alipurduar, usually has a pH between 7 and 8, sometimes a little higher or lower, but circumneutral and shifted towards baseness.

The water temperature there may vary according to the month, with monthly temperatures as low as 10 and as high as 32 degrees. In neighboring Koch Berar, the main river is the Torsa and the climate is similar to that of Alipurduar. The water temperature of the River Torsa was found to vary from 18 to 29 degrees, and the pH is similar to that of the River Kaljani. There is no major river through Barobisha itself, but the neighboring waters assumedly have comparable parameters. Streams in neighboring western Assam can have a pH of 6.4 to 6.6.

Macrobrachium are regarded as omnivorous benthivores, or generalists feeding on a breadth of plants and animals on the substrate. Although plant material is taken, Macrobrachium show a preference for animal protein. Although their 'arms' are long, their 'claws' are proportionally small, thus limiting the damage these shrimp are capable of in the aquarium. Smaller species of Macrobrachium are often considered safe to cohabit with some fish, although fish eggs and small motile animals such as small fish, will likely be seen as food by these shrimps, and they will certainly consume snails. Juveniles of large Macrobrachium species, can kill and consume snails with a shell diameter almost 3/4 of their own length.

Smaller Macrobrachium species will not kill fish their own size, but the larger species of the genus are reportedly able to. Eggs and fry of fishes, and the larvae of other shrimps, will likely be eaten even by the small species of Macrobrachium. Macrobrachium species appear to vary in their intraspecific competitiveness and tendencies towards cannibalism, but each individual requires a sufficient number of opportunities in the aquascape, in which to choose shelter from cohabiting conspecifics. Therefore, although M. agwi can be housed in small groups of conspecifics, they must not be overcrowded, each animal must be able to avoid confrontation, and also retreat to shed whilst they are growing, without facing competition for these refuges.

In some Macrobrachium species, molting shrimp may be vulnerable to cannibalism, whilst they are still soft. Confrontations in members of this genus, can also result in the loss of whole or partial limbs, or other severe damage. Therefore it is important to avoid these animals stressing one another. Smaller Macrobrachium species do not uproot or otherwise seriously disturb plants in the aquascape, although the larger species in the genus can be destructive, especially to delicate plants. In anecdotes from the tropical aquarium trade, these shrimp are often kept in water with a circumneutral pH, and at an appropriate temperature of 18 to 26 degrees centigrade, befitting their origins close to the Himalayas.