Successful breeding of the more commonly imported Sturisoma spp is a fairly common event, and observing their breeding and brood care behavior is a fascinating experience. The spawning may be planned, but more often the fish spawn quite unexpectedly (for the aquarist anyway). In such an instance aquarists find them quite unprepared for the hard part - raising the fry. Below, I share my methods for raising Sturisoma fry and try to provide the reasoning for my techniques as they are different from most methods I have come across in the literature.
In personal communications with Ed Ruiz, my Venezuelan friend who has frequently collected Sturisoma, I have learned the following about the breeding habitat of Sturisoma spp he has collected. In Venezuela they are commonly called “policias” due to the males’ habit of standing guard upright as if at attention on their nests. Ed has observed them spawning in the shallow riffles of small streams in water normally about 12 to 24 inches deep. They typically spawn on an exposed root or slender piece of submerged wood.
I have been a lifelong fly fisherman and fly tier and have a good grasp of aquatic biota as an amateur aquatic insect entomologist. I researched the subject of neotropical aquatic insects and found they were well represented with species analogous to those I have encountered in rivers, streams, and lakes in North America. The richest natural habitat of most aquatic insect larvae is well oxygenated and will have swift water. Therefore, I try to simulate these conditions in my Sturisoma spawning rearing tanks. The insects present include, but are not limited to, caddis flies, stone flies, may flies, and black flies. All of these aquatic insect larvae live on and in the periphyton layer of algae growing on rocks, wood, and sand. My aquarium observations verified that Sturisoma are primarily predators of aquatic insect larvae and that the algae they eat is somewhat incidental to their search for the insect larvae living in periphyton.
I think that the fry of Sturisoma eat the same foods, but due to their smaller size, would tend to eat the egg masses and newly hatched aquatic insects. This is an important distinction because most aquarists consider Sturisoma spp to be algae eaters. They are... but only as a byproduct of their search for small aquatic insect larvae. Many hobbyists try to feed Sturisoma fry a variety of algae substitutes only to see the fry starve in large numbers.
It isn’t easy to supply aquarium bred fish fry with the same foods they would normally exploit in their native waters, so we aquarists have little choice but to search for acceptable substitutes.
My choice of substitute foods for Sturisoma fry lead to experimentation with two foods used in commercial aquaculture for the conditioning of breeding stock. I have found that two foods work very well as the primary diet for Sturisoma adults and fry. Indeed, these foods have proven indispensable for me in breeding and raising many species of loricariid catfish. The two foods are earth worm and Spirulina sticks. The Spirulina sticks are not simply an algae-based food but also incorporate a high percentage of shrimp meal. The earth worm sticks also contain shrimp meal. Why is the shrimp meal important? The exoskeletons of all aquatic insect larvae are composed of the protein, chitin. Chiton is rich in calcium and is a building block in the formation of bone and scutes of all armored catfish. It is also a source of roughage important in proper digestion of foods. Between these two foods, one can provide a fairly well balanced diet for Sturisoma fry. You can actually forget about the use of garden vegetables entirely.
Once wild Sturisoma fry hatch, they leave the deeper water where the nests were. It is my opinion that the fry move down stream to the rocky tail outs of the riffled pools where the adults chose to spawn. This water is only 6 to 12 inches deep. The fry are naturally strong swimmers but they take advantage of the phenomena common to all fast water fish living over a rocky bottom called the “boundary effect.” The boundary effect is when the turbulence of the fast water just above the rocky bottom creates a thin zone of relatively slow water. In the case of the zone where I believe newly hatched Sturisoma fry likely inhabit the zone is only an inch or so thick. It is a place where aquatic organisms have all the benefits of fast water such as high dissolved oxygen levels yet can maintain themselves in this food rich zone with the minimum amount of effort. This preserves their strength to avoid predation or leave in search of fresh feeding grounds. As the fry grow, this ability can be exploited to utilize ever deeper waters. This is an important concept that one must always keep in mind when raising Sturisoma fry.
These are conditions that we must strive to duplicate in the aquarium to raise our Sturisoma fry but we must keep in mind that what is ideal changes as the fry grow and ultimately mature.
It can also be one of the most difficult aspects of creating the correct environment in the aquarium for the fry as they develop.
Recreating a suitable aquarium environment for Sturisoma fry at every stage of their development is an art based on some science. Finding exactly works best for you will require experimentation. I can only share the techniques I have used with success.
I prefer to remove the Sturisoma eggs from a glass substrate or trim a stem or leaf they have placed their eggs on rather than trying to collect them by netting and perhaps risking harming the fry. When the eggs are laid on the glass I remove them at 8 days by using a razor blade scraper and small diameter siphon so I can catch any eggs that fail to adhere to the edge of the blade.
I have always breed my Sturisoma at 84*F and find they generally hatch on day eight. Most unhatched eggs will hatch in the reduced pressure they encounter going through the siphon hose.
I place a net breeder in a bucket and siphon the fry and prehatched eggs into the net breeder. I then hang the net breeder back in the breeding tank. I also place a plastic jar lid about 3-4 inches in diameter and weighed down by a couple of pebbles to form an area to hold food. I feed mostly by using a cheap filter media bag containing a small amount of earth worm sticks and the bag is also weighed down with a small pebble, however the bottom of the bag is kept within three inches of the water surface. Feeding newly hatched Sturisoma fry is not an immediate concern. They hatch with enough yolk sac remaining for them to not need to begin feeding until approximately 48 hours have passed. Some fry may take 72 hours before they begin to eat. The fry will have absorbed all their yolk by then and will immediately begin seeking food. The earth worm or Spirulina sticks soften to a mush within an hour and become soft and fine enough for the fry to use their natural suction to draw fine food particles through the media bag.
I place the return of a canister filter within the net breeder. I use a flared outlet that is adjustable for flow direction set to flow out horizontally. Many fry will gather along the edges of the outlet with their tails waving in the current when they are not actively feeding off the food bag. I also add just a few food sticks in the plastic jar lid as some fry will prefer feeding there as well. Several pebbles should be in the jar lid to not only hold it down but to provide resting and attachment sites for the fry. The fry may be left in the net breeder for three weeks. They feed constantly. This is an important point. Fresh food must be kept available to the fry at all times. Normally the food remains edible for about 12 hours. The food bag should be rinsed clean and restocked every 8 to 12 hours. Begin with very few food sticks as they absorb a great deal of water and expand to many times their size in the dry state.
Three weeks have gone by and your Sturisoma fry should now be nearly three times as long as their newly hatched size and ready to be moved to their own first rearing tank. It is advisable to keep the fry concentrated in small tanks, but still necessary to move them to larger tanks as they grow. Their needs will changes as their development proceeds.
The first tank should be a ten gallon tank (20” X 10” X 12”) filled to six inches deep with 2/3 water from their previous tank and 1/3 new conditioned fresh water. The furnishing of the tank should be several small, 4-6 inch pieces of Malaysian driftwood. It sinks without any need to be soaked and should be rinsed free of any dirt or dust. I also add a few 3-4 inch rocks. Some Java Moss is desirable as well, but not too much as the Moss may collect bits of food which may spoil if it goes uneaten.
The temperature should be the same as the breeding tank (I keep mine at 84*F).
Equip the aquarium with enough light to grow the moss. I also sometimes grow some Hornwort, Ceratophyllum. Be sure to supply intense enough light for this or any other plants you use to remain healthy. The bottom of the aquarium is best left bare to facilitate maintenance. The Sturisoma fry will consume any algae that forms on the glass sides and bottom so the concern that glass will grow deleterious bacteria is unfounded when raising Sturisoma fry. This is more of a concern when raising Corydoras fry.
I would emphasize the importance of simulating a shallow, fast flowing stream environment.
This must be simulated with a power filter and an air stone. I prefer to use a sponge filter of the pedestal type with a small power head running the sponge filter. The ten gallon tank will only be filled to about six inches deep so the sponge filter/power head combination will likely have to be laid over on it’s side. The power head should be adjustable by design or a ball valve should be placed on an extension piece of flexible hose attached to the outlet. The latter is the most desirable solution as it allows one to use the same filter when it comes time to scale up the size of the rearing tank. About 50 or 60 fry may be started in the ten gallon tank. The flow should be strong enough that the fry must swim vigorously to make headway against it. The rocks and wood will provide the fry with plenty of quiet or indirect currents where the fry will rest whenever they want to.
Foods continue to be the same. Continue to keep a food bag as before when the fry were still in the net breeder but also place a few sticks directly in the aquarium. The currents are going to distribute the softened stick food throughout the aquarium and some will collect on the sponge filter. The fry will find nearly all of the food. Within a few weeks the use of the food bag may be discontinued. Exactly when you decide to do this should be based on your observations of where most of the fry feed. The fry will grow steadily but a little slower than they did during their first three weeks in the net breeder. Once the fry average about 1-1/4 inch total length you can safely increase the water depth to ten inches. This will increase the available vertical space for the fry and they may be left in the tank until they reach 1-1/2 inches total length. I would begin to introduce them to some other new foods such as frozen blood worms, a few live black worms, and a real delicacy they will appreciate, live Grindal worms. Chilled newly hatched brine shrimp will be appreciated as well. You can also try offering them Tetra Color Bits but their staples should remain earth worm sticks and some Spirulina sticks. During the grow out period it is wise to do partial, 25% daily water changes using aged or conditioned water. Use these water changes to siphon out any uneaten food and detritus. These daily partial water changes are very important in the crowded rearing tank.
Once the fry have reached 1-1/2 inches it is time to scale up the tank size to a 20 gallon long (30” X 12” X 12”). Fill it with all the water from the initial rearing tank and top it off to a depth of ten inches with aged, conditioned fresh water. You can increase the power head flow rate and add more rocks and wood, but should continue using a bare bottom. You can grow 50-60 Sturisoma fry to nearly three inches in a 20 long and the water depth may be increased to the full 12 inches depth of the 20 long once the fry average two inches total length. Once the fry have attained an average length of three inches total length you should divided the 50-60 fry between two 20 long aquariums. You may introduce a 1/4 to ½ inch deep layer of pool filter sand substrate if you wish. Your three inch juvenile Sturisoma may be grown out to about five inches if you wish in these 20 long aquariums, but they are large enough to be shared or sold once they are at least 3-1/2 inches without great concern. I would add another sponge filter driven by air in addition to the power head driven sponge filter and an air stone. Sturisoma of three or more inches will adapt well to most peaceful, planted show tanks.
Sturisoma do have one negative behavior. They are attracted to the sides of Discus from a very small size. They may be as small as two inches when they begin and they will never stop pestering Discus as they chronically attempt to feed off the skin slime of Discus. In some cases, such as my own experiences with adult Sturisoma with Heckel Discus, the Sturisoma can cause severe skin damage and stress the Heckels to the point of death if there is no intervention. It is best to take my word for it as both a Discus breeder and Sturisoma breeder that Discus and Sturisoma do not mix.
There is further information on this species on the Cat-eLog page.
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