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BREEDING APHYOSEMION SJOESTEDTI, THE BLUE GULARIS
Posted by: Guest on Monday, November 25, 2002 - 05:37 PM
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by Harry Juhlman, RAS
The Blue Gularis is one of the most striking of Killifish, the adult male reaching four to five inches in length and displaying a spectacular metallic blue body accented with patches of deep purple. The large tail is blue on top and vivid orange on the lower half, trimmed with a line of deep purple and a final trace of metallic blue. Current texts show the scientific name of this fish as _Aphyosemion sjoestedti_, although some early publications show the name _Aph. coeruleum_. (My 1966 Innes "Exotic Aquarium Fishes" used the _coeruleum_ name and shows a different killie as _Aph. sjoestedti_.) I have no insight to offer on the scientific naming of these fish, much less the renaming, and this conflict is mentioned only for the benefit of those readers who may wish to look up the fish.
I obtained some young unsexed fry and raised them in a ten gallon tank. As the males began to show their color they were separated into a second tank of the same size, to allow them to spend their energy on growth rather than more amorous pursuits. The fish were fed live food, mostly daphnia and mosquito larvae, as well as flake food (Tetra conditioning). Soon they were also suspected of making food of some only slightly smaller tank companions, which seemed to be dwindling in number. The fish required about three months after the separation of the sexes to reach their full size and, although they likely could have been bred sooner, they were kept separated until they reached full size. When cooler weather set in their tanks were given heaters to keep them at 68 to 70 degrees.
This killifish is a peat spawner and breeds quite simply. In their native environment in Africa, they spawn in mud in small pools formed during the rainy season; the eggs lie dormant during the dry season to await the next rainy season to begin the cycle anew. In the aquarium peat serves as a handy replacement breeding medium. Common garden peat was boiled (to help it sink) and placed to a layer 1/2 inch deep in the bottom of a gallon jar. The jar was filled with aged water, placed in the heated aquarium to maintain temperature, and a pair of fish was introduced. Spawning behavior was observed almost immediately, although enough peat was stirred up that depositing of the eggs was never actually witnessed. The fish were not provided food while in the jar, to avoid fouling the peat, so the breeding setup was only maintained for a few days. After spawning the fish were removed and the water was strained through a net to collect the peat, which was then dried on newspaper for a day and placed into a plastic zip-lock bag. The bag was labeled and put in a closet for storage, as the eggs required a dry period to develop. Several sources recommended that the eggs be kept close to 70 degrees, one even suggesting an incubator be constructed from a foam shipping box and a heater for this purpose. However, the storage space I had kept the eggs close to 60 degrees and provided at least some success.
It should be noted that I never actually saw any eggs. Apparently the peat adheres to them and conceals them.
The eggs were given a full three months to develop and then placed in a jar with tank water to hatch. (The water had salt added at a ratio of 1 tsp/gallon. Many hobbyists insist that this salt addition is extremely important for the well being of killifish. Controlled experiments I have run have failed to show any improvement in either survival or growth with such a salt addition and I remain unconvinced. However, one benefit can be seen when the salt is present in the water of young fry that justifies its addition; baby brine shrimp fed to the fry live much longer with even this small amount of salt in the water.) Fry were observed within hours. The fry were moved with a basting syringe to shallow dishes where they were provided with newly hatched brine shrimp. Shrimp were also provided to the fry in the peat who had managed to avoid the baster.
Unfortunately, the mortality rate was high, slightly over 50%. None of the fry that had been able to hide in the peat survived. The surviving fry grew quickly and for the first monthly daily changes were obvious. Sexual coloring was apparent within six weeks. An unexpected ratio was seen as the males colored out; of eleven healthy killies that matured, ten were male.
The Blue Gularis was only my second egg layer to spawn, and my first peat spawner. Breeding them required only following instructions and the use of common sense. However, despite the losses of fry I experienced I may have been extremely fortunate in having a successful hatch on my first try. A second batch of peat hatched a month later produced only nine fry, none of which survived more than two days. A third batch yielded no fry. Written material suggested that the peat could be redried and hatched later to yield additional fry; this was tried on these three batches of peat but no additional fry hatched. A fourth batch of eggs is now being hatched, and while the yield was in the twenties the mortality rate again looks to be near 50%, with many of the fry laying on the bottom of their containers and failing to feed.
The breeding of a peat spawning killifish is a fascinating and rewarding experience, particularly one as spectacularly adorned as the Blue Gularis. The hatching of dormant eggs on demand by the simple addition of water gives the hobbyist an unusual opportunity to plan the hatch of the fry at his convenience rather [than] at the inopportune times selected by most parent fish.
Reprinted with permission from G.S.A.S. Newsletter, Greater Seattle Aquarium Society, April 199
Note: Published at FishGeeks with express permission from the author. This article can not be copied or reprinted, either physically or electronically without the permission of the author. Copyright 2003.
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