Ghost Shrimp – See-Through Inverts for Your Tank
Commonly sold as feeders for predatory fish (puffers love them by the way), these US Gulf Coast natives are worth a closer look for peaceful tanks with small fish or those with non-predatory habits. They have been suggested on the boards as algae eaters. In my experience this is a bit of an exaggeration. They are omnivorous and will eat some soft algaes if there is no flake or small pellets available but prefer to compete with their finny tankmates for normal aquarium fare or to scavenge the tiny leftovers that the fish miss or ignore. Between meals they will scavenge the tank, making a group of these inverts one of the more efficient selections for tank cleaners, at least where uneaten food is concerned. They are not at all limited to the bottom of the tank. They will forage all over the rocks, driftwood, plants and even the glass sides of the tank.
These creatures are caught along the Gulf Coast in marshes, rivers and less-than-marine bays. Originally seasonal (they are common and easy to harvest seasonally), they are now captured at peak and kept in holding ponds and vats for off-season stock or are “farmed” in ponds or vats. For me they do best in at least slightly hard to hard somewhat alkaline water but if that profile matches your water supply, salt of marine mix is not needed. They do withstand long-term exposure to softer water; so don’t fret about whatever your tank conditions may be, possibly unless you are breeding them or want to maximize their lifespan. In tanks with non-threatening tankmates, these shrimp seem to be active almost 24/7. In a multi-shrimp tank I seem to see activity whenever I look. With threatening tankmates, they will be largely nocturnal in my experience. I have poor results with these shrimp with my larger Synodontis cats that are nocturnal. The shrimp jump or climb out of the tanks — whether being chased or just being spooked by being brushed by catfish whiskers in the night, I do not know. I can imagine this happening with other nocturnal fish, even if they are not shrimp-eaters (my Synodontis are filter feeders, wanting very small foods). These shrimp are not the escape artists that crayfish and fiddle or re-claw crabs are but they are no slouches at finding escape points from the tank, so check as far as possible for easy ways out and block such.
There seem to be at least two and probably several species of Ghost Shrimp carried by local fish stores routinely as feeders. The two main divisions I find hard to tell apart. One is true freshwater (FW) and appear to be a Paleomonetes species but will withstand brackish without problems. The other is brackish to marine, but will withstand FW for extended to indefinite periods. The real FW Ghost Shrimp (which still may be more than one species) breeds readily in tanks, the female attaching fertilized eggs to her swimmerets after a fresh molt. The female carries these with her until they hatch, fanning her swimmerets periodically to clean and oxygenate the eggs, which individually are fairly large. Development of the eggs/larvae can be seen as darkening of the eggs as the enclosed embryos mature. When the female releases the larvae, they are individually tiny, just barely visible. The planktonic (floating stage of larvae) is quite brief in the species I kept longest, they settle out very quickly. If they do not, feeding and filters may be a bit tricky, The settled out young are miniatures of the adults. They can take fine fry food such or the finest powders or even newly hatched baby brine shrimp almost immediately. However, for me they do better with live foods (infusoria) available in their tank and live newly hatched brine shrimp supplements. The adults (along with any fish in the tank) will consider the babies as sushi, so survival is likely only in the most heavily planted tanks, or better in isolation tanks. If you set a tank for hatching with a near-term female carrying eggs as the only inhabitant, watch her and remove her as soon as possible after the fry are released. She will have no objection to cannibalizing her own offspring. Heavy planting here as well gives more refuge, and a richer source of infusoria for the fry to graze. The length of time for the eggs to develop to hatching is variable with temperature. Three weeks from the last molt seems about normal at temperatures in the mid to upper 70s F. For me these shrimp seem to need at least moderately hard (7-9 GH, calcium and magnesium hardness) and KH in the same range or a bit higher. These are the parameters of my current water supply. Harder water (higher GH and KH) will likely be even better. Years ago, attempts to breed these in softer water were not very successful but this could well have been contributed to by other uncontrolled or un-noticed factors. All filters should be sponge-protected if you don’t want to risk the fry. The sponges make excellent grazing sites for the shrimp as well, with captured food particles and infusoria feeding on the microflora and fauna on the sponge surfaces. These fry are the invert equivalent of small Tetra or Rainbow fish fry. Masses of Java Moss are a wonderful nursery – these harbor loads of infusorians and provide plenty of refuges at the same time.
The other common Ghost Shrimp, the brackish/marine type, also breeds in captivity, but the “fry” are quite different from the adults, true larvae, tiny even in relation to their FW kin and live free-floating in brackish to marine water, drifting with the plankton eating the tiniest plankton. They go through multiple molts and life cycle stages during this period, so are extremely difficult to rear in captivity. They live this free-floating existence for many days to weeks before they come to resemble the parents and settle out of the water column to an adult life style. If you have seen both types of females carrying eggs on their swimmerets, the difference is obvious. The brackish/marine forms have tiny, tiny eggs and many, many of them. The eggs of the FW species are much larger and even to aging eyes can be seen as individual eggs (well, on occasion with the help of a magnifying lens).
Both these shrimp types are all but transparent. Their shells are clear, their muscles very nearly so. The hindgut contents are clearly visible. If they have been grazing algae, then get a belly full of colored-flake food meal, before too long a dividing line in the color of the hindgut is noticeable. Once they die or if they are ill or severely stressed to near-death, they become translucent white. Sometimes they even turn pinkish, as do boiled edible shrimp and lobsters after death. As with other crustaceans, when they grow they shed their external skeleton, after developing a new, larger one. In very soft, low calcium water (and possibly low iodide water but that is still controversial) they sometimes have trouble shedding the old exoskeleton, occasionally becoming trapped in the partially shed shell. They or their con-specifics, frequently but not always consume the cast-off shell (recycling). They are agile swimmers, and in common with many relatives, can snap backward at great speed from a startle reflex forward snap of their tail.
There are commonly other types of shrimp in batches of ghost shrimp – I have pulled out several long-armed types (Macrobrachium species) from LFS batches. Those are not shrimp for peaceful community tanks. Their longest claws are much longer and a bit heavier than the ghost shrimp. They are likely to show a bit more color as well, especially on the arms or claws. Interesting in their own right, they are not peaceful tank inhabitants as a rule.
Due to their seasonal low prices and ready availability, these ghosts are fascinating creatures for early forays into invert keeping. They can inhabit any size tank but for watching a dozen or so of them on their own, a 15-gallon tank is near ideal, a ten will do for a smaller group. The fine particles at the bottom of your used-up flake food containers are ideal staple food. If your area is iodine-deficient, adding a few drops of marine/reef iodide supplement every month would not be bad, especially if you have experienced molt problems with your shrimp. An alternative would be a teaspoon or so if marine mix per month in the tank to serve the same need. If you want to try your hand at planted tanks, these are perfect inhabitants for the novice invert or plant keeper. It you have will power, hold off on tankmates other than possibly MTS snails or Otocinclus cats. The Ghost Shrimp are not nearly as good at algae clearing as are Amano shrimp but they cost a tiny fraction of the price of an Amano and are almost as hardy but not as long-lived, about a year and a half seems to be average. They can reach two inches but are usually smaller (population, food and water quality are all factors here). Keep a species tank of them for a while, then set up a second, smaller tank and try your hand at breeding and rearing inverts. They are not worthwhile trade goods at the LFS due to their low unit cost, but lots of fun and personal satisfaction from something quite different from a guppy tank.
RTR/Robert T. Ricketts, Jr.