Because of the variety of new and specialized fish food products, fish owners rarely think about raising food for their pets, but it is quite possible to do. Although you should have some experience with a saltwater system as well as a certain level of creative innovation for such an undertaking, raising live food such as brine shrimp can be rewarding.
Brine shrimp are a popular species to culture at home because it is relatively easy to keep a population of them – especially if you know a little about how they live. These zooplankton are also called artemia, and like shrimp, crabs and lobster, are a kind of crustacean.
Following these basic guidelines and combining them with your experience, you can maintain a healthy stock of brine shrimp. Once you’ve tinkered your way to a system that works, you can just kick back and watch yet another of nature’s scenes unfold as your fish chase after and gobble up their homegrown prey.
You should begin with a 10-gallon glass tank. Take a thin sheet of acrylic or formica, slightly bigger than the tank dimensions and jam it into the bottom of the tank so it creates a concave surface. Seal the seams around the acrylic with silicone. You want to eliminate corners which become dead spaces that will inhibit water circulation and collect hatched shells and other waste. To enhance circulation, depending on how creative you want to get, you can glue a partition in the center of the tank, forming a raceway.
Circulation and Aeration
Setting up a circulation system can be tricky. To grow healthy adult brine shrimp, strong aeration and good water circulation are essential. You will need to come up with a way to rig your pump so that water is continually circulating through all regions of the tank. If you use airstones, use only those that make large bubbles because brine shrimp will ingest small air bubbles (or they lodge in their swim-appendages), which forces them to the surface where they will eventually die.
Lighting, Temperature and Water Quality
Brine shrimp are attracted to light so use a low light level, otherwise they will expend much of their energy (which lowers their quality) in an effort to remain near the light source. A 60- to 100-watt light will suffice but hatching will require higher light levels (2000 lux constant illumination). Optimal temperature conditions range from about 77 to 86 degrees Fahrenheit, depending on the strain that is cultured. They prefer a salinity between 30-35 ppt and a pH of around 8.
To keep water quality adequate, change about 20 percent of the water each week and clean the bottom of the tank every few days. To do this, turn off the air and let the tank settle. Shine a flashlight at the surface and wait a moment as the artemia are drawn to it. Siphon off the material on the bottom, consisting mainly of molted shells.
Start out by purchasing a packet of dehydrated brine shrimp cysts at an aquarium or pet shop. These cysts can stay viable for many years, providing they are kept dry and unexposed to the air – a container in the refrigerator keeps them well. The cysts contain dormant embryos that will resume their development once they have been placed in water.
After 15 to 20 hours in water that is about 77 degrees Fahrenheit, the cysts burst and the embryo leaves the shell. In this “umbrella” stage, the embryo hangs beneath the cyst shell, still enclosed in a membrane.
Once it separates from its shell, it becomes a free-swimming young shrimp called a nauplii. It is brownish in color from the yolk it carries to complete its development. After about 12 hours, these nauplii molt and begin to feed normally, filtering tiny particles such as microalgae and bacteria, out of the water.
It takes about eight days and 15 molts for nauplii to reach adulthood. In low salinity and good food conditions, females will produce 10 to 11 broods of a few hundred free-swimming nauplii over about 50 days. Adult brine shrimp get to be about 8 mm long, but in the right environment can reach 20 millimeters.
Throughout their lifecycle, brine shrimp change in quality, a big consideration for the aquarist. Newly hatched shrimp are rich in fat (about 23 percent dry weight), which is used up as they develop (dropping to about 7 percent as pre-adults). Adult brine, however, are high in protein: about 63 percent compared to 45 percent for the nauplii. So, if you have young fish, which require a high-fat diet for growth, you need to harvest nauplii. But if your tank has many older juveniles and adults, which require a high-protein diet for health and reproduction, adult brine shrimp are better.
Harvesting Your Brine Shrimp
To harvest the nauplii, turn off the air and let the stock settle for about 10 minutes. Hatched empty shells will float to the surface; unhatched cysts will sink to the bottom. The napulii will also concentrate on the bottom. Since they are attracted to light, use a flashlight to herd them to where you can scoop them out with a paper cup. Harvesting the adults can be done in much the same way, and the larger adults can be caught in mesh nets. Unhatched cysts can be collected and used for another batch or saved in case something goes wrong and you need to start over.
Brine shrimp are filter-feeders and consume particles in the water column as well as inert nutrients. Newly-available enrichment formulas such as Selcon are highly recommended, but you can feed the shrimp fish meal, egg yolk, whey, soybean powder or wheat flour. Dried algae such as spirulina can also be used. Do not overload the tank with inert foods, it leads to fouling and low oxygen levels. Continuous drip-feeding is best. Small amounts several times a day also works.