Article © Eric Thomas, uploaded June 15, 2016.
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Hiding in the sand, only nose and tail visible.
Background
Some fish you buy to watch, some fish you buy to breed, and some fish you buy because they are different. When we first bought two banjo cats, we bought them because they were different - they were "cool." But like so many other catfish, it turned out that when you own banjos, you don't get to see very much of them, because they spend most of the day in hiding. For banjos, this means buried in the sandy bottom of our aquarium, with nothing more than their mouth and nostrils, their eyes, and the tips of their tails protruding out from the sand. Even so, we liked our banjos, so after a while, we bought a couple more to bring our group to four. In hindsight, we wanted to have more of a fish we never saw, I suppose because we liked what we couldn't see.
The aquarium
Our banjos were housed in a 36 gallon Aqueon bowfront aquarium set up as a community tank; besides the banjos, there was a hodgepodge of other fish: a few albino Corydoras aeneus, two C. trilineatus, several cherry barbs, five silver hatchet fish (another oddball we really liked), two upside-down cats (Synodontis nigriventris), two or three glowlight tetras and a flying fox. This tank was setup as a new joint project for my young teenage son and me. Some of the fishes were his, and some were mine. The banjos were his idea, but I liked them so much I considered them mine too. Since this was a community tank, the fish received a mix of foods: typical flake food, live Tubifex worms, and NLS Thera A+ 1mm pellets were the most common foods provided. Since we rarely saw the banjos, we didn't know exactly what they were eating, but they were growing, so I know they ate well.
As mentioned above, the tank had a sand substrate, about 2-3 inches deep (standard play sand from a local hardware store); decorations included some driftwood, and lots of live plants (Amazon swords, banana plants, chain swords, Anubias and Cryptocoryne). Most of these plants were purchased in plastic pots, and we didn't bother to remove the pots - we just put the plants right in the tank, so that about half of each plastic pot was exposed above the sand level and the rest of each pot was buried in sand. The centerpiece of the tank was a resin crashed Blackhawk helicopter, which became the preferred hiding place for the upside down synos (the helicopter was my son's idea).
Water conditions
Back then, we were just happy to keep our fish alive - we didn't do anything special to the tapwater, other than treat it with Novaqua to remove chlorine. The wood caused a dark staining of the water, and the pH would drift down into the 6 range, sometimes even below 6.0 into the mid pH 5 range, and other times, especially after water changes with fresh tap water, the pH would rise up to the high 6's (pH 6.7-6.9); most of the time, though, the pH was between 6.0 and 6.5. Aquarium temperature was kept around 77°F using an internal submersible heater. We would perform water changes about every other week, using a garden hose to drain out about 50-75% of the water, and refill the tank using the same garden hose, attached to an outdoor garden spigot. The outside water was often much colder than the aquarium, at or below 60°F, but we didn't know better, and we figured the aquarium heater would just reheat the new water in no time at all. So we would just top off the tank with this really cold water. None of the fish seemed to mind too much, although I think they may have been swimming a little slower in the hours following each water change. With regard to filtration, the tank was equipped with an Aqueon QuietFlow 50 HOB filter. This created a really strong downward water current along the front pane of the glass, which the corys and the banjos seemed to like.
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Adult male
Adult female
Hatchery tank, with plant covered in cory and banjo eggs
(only cory eggs are visible in this photo).
Big surprise - the first spawning
One Saturday morning (10 November 2012), a day or so after one of those cold water changes, we awoke to find our albino corys laying eggs in large masses on the aquarium glass, mostly behind the heater and HOB filter intake tube, but also on the front glass by the water current. We could also see some cory eggs scattered on the leaf surfaces, among the plant roots, and even stuck to the plastic plant pots. Fearing the other fish would eat the eggs, I used a semi-rigid plastic ruler to scrape the cory eggs off the glass and I transferred them to a 2.5 gallon aquarium which we hurriedly set up as a hatchery tank; this hatchery tank had some of the sand from the community tank, plus an airstone - no heater and no filtration. I also removed all of the plants which had eggs attached to them, taking their entire pot out of the main aquarium, and I transferred all the plants with eggs to the hatching tank.
Eggs hatching.
After several days, the eggs began to hatch. Lots of albino cory fry, some pigmented cory fry (C. trilineatus), and three or four really weird dark fry, almost black... These were baby banjos! We'd never had any fish spawn before in this tank (it was my son's first time too), and here we had THREE SPECIES SPAWN AT ONCE! Yippee! But most significantly, who would have imagined that someone could breed banjo cats in captivity? Okay, moment of truth - we didn't breed banjos in captivity, THEY bred themselves! We just happened to be the proud owners of these fish.
Raising the fry
For first foods, I used a mortar and pestle to pulverize a mix of Aqueon color-enhancing fish flakes, New Life Spectrum Thera A+ 1 mm pellets, and a generic spirulina pellet; these were all mashed together to form an extremely fine dust. I fed the fry 2x day. I changed about 1/4 of the water in the hatchery tank every week - probably not the best approach because we had no idea then how important clean water was to baby fish. The baby C. trilineatus did not do well; all but two or three died, but fortunately the baby albino corys and the baby banjos didn't seem to care as much about water quality; they grew... they grew fast. After a few weeks, I started the juveniles on live Tubifex worms. The baby banjos would get a small piece of a worm in their mouths and just sit there - a 10 mm banjo would sit there forever it seemed, with a 30mm long Tubifex worm dangling out of its mouth. Eventually the banjo would sever the worm's body and swallow whatever was in its mouth. As they grew larger, the juveniles fed ravenously on live Tubifex worms and on NLS Thera A+ 1mm pellets (intact, not pulverized).
These spawnings happened several more times over the course of a year, but each time we never saw any of the events leading up to the banjo spawns. However, we did discover that the banjo eggs look different from cory eggs. Banjo eggs are smaller than cory eggs, about 1-1.5mm diameter, with a green color to them in contrast to the off-white, slightly yellow color of albino cory eggs.
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Courtship and breeding behavior
The banjo eggs were usually stuck to the plants and pots, sometimes to the glass, but always near the level of the sand, never high up on the walls of the tank like the albino cory eggs. This led me to believe that the banjos purposefully laid their eggs on the plants and pots, just like corys do. However, one morning I awoke early and happened to be in front of the aquarium when the automatic timer activated the aquarium light at 6:00AM. Over the next 20 minutes or so, I was privileged to witness banjo spawning step-by-step:
Courtship.
Their courtship had started overnight while the lights were still off, and continued even after the lights came on. When I first inspected the tank in the morning, I found the female and male resting on the sand. The female swam to the male and nudged him; he pursued her around the tank, always slightly behind her and underneath her. They both started swimming upward toward the water surface; she was slightly ahead of him as they swam (1). It looked to me as though he was nudging her or biting her on her side near her pectoral fins, just behind her operculum. She responded by bending into a sideways, inverted U-shape, her body wrapped over the nose of the male, with her head slightly downward (2). They both continued to move upward, the male pushing the female up ahead of him, while he continued to nudge or bite her on the side. All of a sudden, she rotated her ventrum upward so that her vent pointed to the water surface and she explosively released a plume of eggs, like a volcano erupting (3). I suspect the male released his sperm at the same time. The eggs shot up a few inches towards the water surface, but then slowly sank back down to the bottom of the tank. As the eggs settled, they adhered to anything they touched - the aquarium glass, plants, driftwood, and even OTHER FISH (mom and dad included); many eggs landed on the sand and became coated in sand. After releasing her eggs, the female and male seemed to lose interest in one another. Within 5 minutes, they had both burrowed back under the sand, staying there for the rest of the day. I picked out as many eggs as I could. On this particular occasion, most of the eggs landed on the sand and quickly became coated with sand around their jelly coats. I used a turkey baster to retrieve these eggs, but none of these hatched for me. I retrieved about 50 "clean" eggs (not covered with sand), but I know I found only a small fraction of the eggs - if I were to guess, I would estimate that there were between 150 and 200 eggs released that morning. Of the 50 or so clean eggs, almost all hatched and I was able to raise about 44 or 45 banjos from that one spawn. For later spawns, I've used submerged spawning mops, positioned just above the sand, to capture the eggs as they drift downward. So that's it. Our banjos have continued to spawn for several years now. However, I've never again had the good fortune to witness the moment of egg release. And since there are so many other fish in the tank, I have not recovered eggs from more recent spawnings.
Spawning mop, held in position by one string attached to a stainless-steel fishing weight beneath and by second string attached to a floating cork above.
If I were to purposefully set up a tank to spawn banjos again, I would use a tall tank (giving the parents height to swim upward), a strong downward water current against the glass, and a sandy substrate. I would also decorate the aquarium floor with lots of removable objects - plants, spawning mops, even rocks and other decorations - anything which can be an adherent surface for the sinking eggs, and which I can remove easily to transfer into a hatchery tank. I suppose I could try to leave the eggs with the parents, but I don't think they will survive well: In the four years we've owned and spawned banjos, I have never had a single juvenile in the parent tank (keep in mind there are plenty of other hungry mouths in that tank too). If you try this yourself, I wish you luck. Enjoy your banjos!
There is further information on this species on the Cat-eLog page.
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