Raising Mysid Shrimp as a Home Aquarium Food

By Jay Hemdal - Aquarium Curator, The Toledo Zoo

Various species of Mysid shrimp, also known as opossum shrimp, have been collected or cultured as a live food for aquatic animals which prefer living foods, such as seadragons, seahorses and pipefish. Many other species of fish relish the addition of Mysids to their diet, but difficulty in producing these crustaceans in sufficient quantity generally relegates their use to only the most critical cases. The method described can produce over 2000 Mysidopsis bahia per week with a time investment of less than 45 minutes per day. Equipment cost is minimal, and the only operational cost of note for this system is the substantial use of Artemia nauplii as a food source.

Culture Area:

Using a rearing area with 80 - 100 square feet of floor space, establish three 30 gallon aquariums and ten 10 gallon tanks with synthetic seawater (at a salinity of 21 to 22 ppt) and air-driven biological filters. It helps to pre-establish the bacteria in the filters by running them in the sump of another marine system for three to four weeks prior to this time. An Artemia system capable of hatching from 8 to 10 grams of cysts (dry weight) per day is also required.

Beginning the Mysid Culture:

A starter culture of around 200 captive raised young adult Mysids is added to one of the 30 gallon brood aquariums. These are fed newly hatched Artemia nauplii "at liberty" twice a day. When they become sexually mature, their young are removed twice a day, just prior to each feeding. The young Mysids are housed in the ten gallon rearing aquariums at a density of between 1200 and 1300 per tank. A new rearing tank is started when the last one reaches that density. When all ten rearing tanks are filled, room for new baby Mysids is created by harvesting the oldest rearing tank and utilizing it as fish food. When the first tank of collected young Mysids reach 4 to 5 weeks of age, about 200 of them are used to set up the second 30 gallon brood aquarium. Continue collecting young from both brood tanks and then after another month or so, select another 200 young adult Mysids and use them to set up the third brood tank. The culture should now be at peak production. At some point, productivity in the first brood tank will start to decline as the Mysids reach old age. At that time, the old adult Mysids are removed, the brood tank cleaned and 200 young adults are selected from one of the rearing tanks and set up in the first brood tank. In this way, a fairly constant, highly productive culture can be maintained.

Husbandry:

Despite their widespread use as pollution bio-assay organisms, Mysids are not too demanding in terms of water quality (as long as the values remain within a reasonable range). No unusual mortality was noticed in tanks even when the ammonia concentration approached 1 ppm.

Average water quality for mysid culture tanks:

Temperature = 75°F
Salinity = 20–22ppt
pH = 8.2
Light = 75 foot-candles
Ammonia = 0.1 mg/l
Nitrite = 0.01 mg/l

Artemia Culture:

Prior to being fed to fish, Mysids should be fed Artemia which has first been fortified with Super Selco. Fortified Artemia can be fed to the Mysids at every feeding, but since this is a very time consuming and expensive process, routine Mysid feedings can be done with "bulk Artemia" as follows:

  • Using an inverted, clear two litre soda bottle (with a cap) with a 1" hole cut in the bottom, add 6–8 grams of Artemia cysts, four tablespoons of sea salt and fill with tap water. Add an airline and harvest after 28 hours by removing the air line, letting the bottle settle, and slightly loosening the cap over another container. Let the settled nauplii run into the container, and tighten the cap back on before any of the empty cysts flow out. Strain the nauplii through a brine shrimp net, rinse with clean seawater and feed out immediately.

Hints and Tricks:

  • Three models of sponge filter were tested: All became clogged with Artemia naupulii, and needed to be rinsed out in seawater every week or so. Eventually, the sponges became too clogged to be easily cleaned. Bio-filters were constructed using plastic deli cups, 1" rigid tubing and bio-media (figure 1) which did not clog as readily.
  • Various hydroids and other "pests" can show up, (mainly in the brood aquariums) and need to be removed by stripping down that tank. At the very least, these hydroids compete with the Mysids for food, and at the worst, they may actually consume juvenile Mysids.
  • When productivity is low, start up a new rearing tank after seven days, even if the target level of 1200 baby Mysids has not yet been met. The reasoning is that if there is more than a one week age difference, the older Mysids will prey upon the newly added ones.
  • Surplus adult Mysids can be frozen for later feeding, or added live to a large holding aquarium, as sort of a "rainy day fund".
  • The best way to remove larval Mysids from the brood tanks is by siphoning them out using a flame polished glass tube attached to a length of 3/16" airline tubing. With practice, an aquarist should be able to siphon out the babies at a rate of better than 20 per minute. The trick is to avoid wasting time trying to siphon out three or four day old babies, they are just too fast. Focus on the smaller one or two day old ones that are positioned on the glass of the aquarium. Free-floating babies are able to escape the siphon in any direction, making them harder to capture. Mysids crawling along the glass can only escape along a 180 degree plane, away from the siphon.
  • Although time consuming, productivity in the brood tanks can be enhanced by selectively removing most of the male Mysids. This reduces predation of the larva as well as the amount of Artemia needed as food for the breeders. With a small net, capture the majority of the Mysids which do not show the female's white brood pouch. You may remove some non-breeding females with this method, but the majority will be males. Even a 10:1 ratio of pouched to non-pouched animals will produce well.

Mysids as Food:

Most zooplanktivorous fishes relish live Mysids in their diet. Once accustomed to capturing the shrimp, most fish seem to feed on them with much more vigour than they show for other foods. In one case, two Red backed butterflyfish, (Chaetodon paucofasciatus) were first offered live adult brine shrimp. These the pair consumed at a calculated rate of 30 per minute. When the butterflyfish were then immediately offered live Mysid shrimp, they consumed these at a rate of 65 per minute. Some degree of caution may be in order as these butterflyfish attacked the Mysids with such ferocity that their snouts became bruised from repeatedly hitting the tank walls and bottom as they captured the shrimp. It is unknown if this vigorous feeding response is due to the good "taste" of the Mysids, or if the shrimp's swimming behaviour more closely matches that of a zooplanktivore's normal prey.

Although the nutritional profile of Mysidopsis is not known by the author, anecdotal reports indicate that as a food item, they are vastly superior to Artemia in both acceptance and nutritional value. A group of new-born Hippocampus which had been fed Artemia naupulii for the first six weeks were gradually wasting away. Mortality ceased once small Mysids were offered as the sole food. Captive husbandry of seadragons requires ample supplies of live mysids, with no other substitute seemingly available (Paula Powell, Dallas World Aquarium — personal communication).(NOTE: THIS IS NO LONGER TRUE - Marc)

Brine Shrimp Enrichment With Liquid Selco

1. Add two level tablespoons of salt to one liter of tap water in blender (This equals a S.G. of 1.020).
2. Shake container of Selco: Fill the 1 gram spoon with liquid Selco (by pouring the Selco into the spoon, not by dipping the spoon into the container of Selco).
3. Add the Selco by rinsing the spoon into the water, and blend for 3–5 minutes.
4. Strain live brine through a plankton strainer, and add to the Selco enriched water. Add another liter of water to which two tablespoons of salt has been dissolved. Aerate for 24 hours, then feed out.

Addendum:

Some public aquariums have developed a different larval separation technique: Using differential net material. In most cases, this simply consists of capturing the entire contents of a brood tank in a standard fine mesh white aquarium net. This material is then rinsed through a standard green mesh aquarium net into an empty rearing tank. The adult mysids remaining in the green net are returned to the original brood tank, and this process is repeated every few days.

Benefits: Much faster than individually siphoning out the larval shrimp one at a time.

Drawbacks: No real ability to keep track of how many larval mysids are being collected. More stress on the adults due to repeated netting procedures. A wider age range of larva are collected, meaning that the older ones will cannibalize the younger, smaller ones in the rearing tank. In real application, it has been reported that since the larval separation method is so fast, (just swoop a net) that aquarists are not spending as much time observing the colony and noting how many larva each brood tank produces in a day — and this is the first, and sometimes only sign of impending colony crashes.

My recommendation is that aquarists first "learn the ropes" by closely following the original culture method as outlined above, and then as their experience level warrants, begin using the net separation technique on some of the brood tanks (but not all of them).


Suppliers of Mysid Cultures:

Aquatic Research Organisms
Mark Rosenqvist
1-800-927-1650

Chesapeake Cultures
Elizabeth Wilkens
1-804-693-4046

C-K Aquaculture
1-318-797-8636

Aquatic Indicators
Ray Less
1-904-829-2780
(Commercial accounts only)

Most recent revision: 2002

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Jay Hemdal & Seahorse.org
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