Spawning Report: Enteromius hulstaerti (African Butterfly Barb)

Enteromius hulstaerti (African Butterfly Barb) Breeding Report

Submitted by Patchin Crandall Curtis

The beautiful, diminutive African Butterfly Barb has been on my target list ever since reading about Hans-Georg Evers breeding of this delightful little fish in the May/June 2014 issue of Amazonas Magazine. They hail from the Democratic Republic of Congo (formerly Zaire) where there has been ongoing civil unrest since 2004 and currently suffers from the second largest Ebola virus outbreak to date. It’s understandable that these fish rarely enter the hobby. When they suddenly became available, along with Enteromius jae, from The Wet Spot I quickly snatched some up. A colony of 12 African Butterfly Barbs was purchased on 5/29/2018. They proved to be quite accomplished jumpers and one year later there were only 7 adults left: 3 males and 4 females.

These fish are frequently listed as ‘Barbus’ hulstaerti, but are now correctly referred to as Enteromius hulstaerti. The genus Enteromius was originally erected in 1867 and recently was revised by a number of ichthyologists. For an excellent overview, see Hayes and Armbruster (2017): The Taxonomy and Relationships of the African Small Barbs (Cypriniformes: Cyprinidae). Copeia, 105: 348-362. Hayes and Armbruster (2017) believe that It is likely that Nicholsopuntius will be elevated for E. candens, E. hulstaerti, and E. papilio.

Butterfly Barbs inhabit slow-moving, shallow, shady rainforest streams with soft, tannic water and dense marginal vegetation. According to Seriously Fish, they tolerate water temperatures of 63o – 76o F and require an acidic pH of 5.0 – 6.5 and very soft water. My colony is kept at water temperatures of 67oF in the winter to 71.5oF in the summer, and a pH of 6.8 – 7.5. The water is charcoal-filtered and soft. They have been thriving and spawning in these conditions. When I first received the wild-caught fish, I heated the tank to 76oF for a prophylactic parasite treatment, and the fish definitely seemed sluggish at those warm temperatures. Since I had no particular reason to believe they had parasites, I stopped the treatment at the end of 5 days, removed the heater, and they perked right up.

Temperature is also important for spawning as most breeders (according to Seriously Fish) have found that if the eggs and fry are raised above 70 – 71.6°F the majority of them will turn out to be male whereas if they are maintained within the range 62.6 – 68°F a more even, and desirable, spread of genders results.

These fish may be very tiny, but they are larger and more visible than Boraras species and definitely have outsize personalities for their length. The females are beautiful pearlescent pale to medium pink with 3 dramatic black blotches on their sides to match their dramatic black eyes. The males are a deeper pink with the addition of bright yellow stripes in their dorsal, ventral, and anal fins. They have the same three black blotches until they come into spawning condition when the blotches merge into a solid black bar. When I first saw this I thought they were dying, but no, they were just trying to impress the ladies. The fish mostly stay quiet taking refuge in java moss or spawning mops during the day but come out to eat with gusto. In the early evening things really liven up, and this is when spawning activity takes place. The males display to each other, but I’ve never seen them lip lock or harm each other. They just dance and dart around each other. The males will then single out a particular female and spend hours enticing her to spawn and chasing other females away.

2018 Spawns Unsuccessful

Four 4 gallon cube tanks were outfitted with corner mattenfilters and cycled before the Enteromius arrived. The Buttefly Barbs were put together in a single tank with a bare bottom, a clump of java moss, some oak leaves and later magnolia leaves and crepe myrtle bark. No heater or lights were used. The fish were extremely tiny when they first arrived but within 3-4 weeks they were adult size, and the males were regularly sporting spawning colors. At this stage, it becomes very easy to sex the fish, although the yellow finnage on the males is also tell-tale.

In November, 2018 I noticed the first cloud of fry in the tank. Unfortunately, this was right before Thanksgiving and I was on my way to Connecticut for several days. When I returned, as I feared, the adults had eaten all the babies but one. A couple months later, a single juvenile appeared in the tank, probably from this first spawn. This species is known for cannibalizing its young, so it was no surprise. If the adults are being well-fed you have one, maybe two days, to separate out the adults from the fry.

In December, 2018 there was another cloud of fry. I didn’t have another tank ready immediately to accept the fry so I just fed them really well with vinegar eels and microworms. At the end of a week, there were still 13 fry and the adults seemed to have decided that these 13 could live. Alas, it was not meant to be. I inadvertently fouled the tank with too many microworms in the evening. When I came down the next morning the tank water was cloudy, all the fry were dead, and so were two of the adults. I was now down to 2 males and 3 females plus the juvenile. Given the unlikely prospect of sourcing more fish in the face of the Ebola outbreak in DRC, I started getting nervous and became more determined to get a successful spawn.

2019 Brings Success

Despite taking good care of the fish in January, there was no spawning activity. So the second week of February, I prepared three 4g cube tanks for them each with fresh leaves, bark, and java moss with the intention of rotating the breeding colony to a new tank every week and waiting to see if fry appeared in the most recently vacated tank. This strategy worked. I left them in the first tank for 1 week, then moved them. One day later a large cloud of fry (>30) appeared in the vacated tank. After one week in the new tank, I moved the colony again. This time no fry appeared. Perhaps the females needed more time to recharge or perhaps they ate all the eggs. I moved the colony a third time, and a few days later 4 fry appeared. I grew out the fry in the 4g tanks. Their first food was biofilm, then vinegar eels for a few days, then microworms, then rotifers and paramecium, then after a few weeks I experimented with baby brine shrimp. They weren’t given more than just a few brine shrimp nauplii at a time until I was positive that even the tiniest fry could eat the BBS. This was to avoid having too large a size differential among the fry which might have resulted in cannibalism. Interestingly, paramecium remained their very favorite food. The rotifers and baby brine shrimp were definitely relished but were easy to catch. Paramecium, on the other hand, required strategy and technique to hunt, and it was fascinating to watch the individual fry perfect their various hunting techniques.

The fry achieved their adult size within 3 months. I haven’t done a detailed count, but there appears to be about two dozen (they can and will jump through the smallest opening) and a good distribution between the sexes. In mid-June the young adults were all moved to a 15g cube tank aquascaped in the botanical style with spiderwood, anubias, cryptocorynes, a sand substrate, and a corner mattenfilter.

Meanwhile, I divided up the original breeding colony into two 4g tanks with one male and one female in each. I’m trying to get another good-sized batch of youngsters before I retire the original colony and try breeding the next generation.

The spawn can be verified by Raychel Upright.