Volcano Rasbora, female above, male below, Photo by Darrell Ullisch
At the 2005 December meeting of SWAMAS I purchased 6 young fish labeled as Rasbora “volcanum” (vulcanus). They were peaceful, active, and similar in shape to a Scissortail Rasbora with a reddish-brown translucent body color. Labeled as “Volcano Rasbora” and a new species, I looked them up on the Internet but could only find a couple of references and very little information. Nothing about them was in my reference books either. They truly seem to be a new and recently imported fish. I did find out that they come from central Sumatra, are benthopelagic (bottom dwelling-open water habitat), and were described by Tan Heok-Hui in 1999. We certainly are fortunate in SWAMAS to have access to rare and new species like this!
The first thing I learned about this fish is that they jump! I put them in a 10 gallon tank with some danios and later discovered there were only 4 of them. They are a schooling and very active fish and are quite difficult to catch in a net because of their quickness. They will eat just about any kind of food, including flake food, frozen brine shrimp, and live foods. This is quite an attractive fish which has a dark lateral line the full length of the body with a light red color in all fins. There is a reticular scale pattern on the sides similar to barbs. Males have a red cast over their body that gets more intense at spawning. Mature females are easy to determine because they have a golden hue over the body and a fuller abdomen. Both sexes have shiny, reflective scales under proper lighting. Adult size of the fish I have is 1 ¾ inches, although they probably are under 2 years old and likely will get a bit larger.
Breeding them proved interesting. The 10 gallon grow-out tank was set up with a sponge-gravel filter on one end and the other end was covered with a layer of large ¼ to ½ inch gravel (instead of marbles) to collect any eggs that might be laid. 2 small potted plants, Java moss, floating hornwort, and najas grass were used on the gravel end with the filter end open for swimming and feeding. Water temperature was about 75 degrees. Periodically I would run a small siphon through the gravel to clean up debris and check for any eggs. A clear bottomed pan is used and the eggs are identified by shining a flashlight up through the siphoned water. For months and months, no eggs were found. About 2 months ago after a water change, I noticed more activity in the tank. The 4 R. vulcanus were darker in color and there appeared to be 3 males and 1 female spawning in the plants in usual barb fashion. I quickly got out my siphon and ran it through the gravel to collect eggs. Eventually I collected about 200 tiny, crystal clear, non-adhesive eggs. I had guessed that they would spawn in soft acid water and was waiting to set them up with that later, when they spawned in Grand Rapids (medium hardness) tapwater. With a good number of eggs, I decided to compare different hardness waters for their hatching and raising. RO water produced an excellent hatch and growth rate of fry. My tap water produced somewhat less of a hatch, and the growth rate of the fry was considerably less, even in 50% RO water. The tiny fry seemed to require some infusoria at first, but they soon were taking baby brine shrimp. This could be a first breeding of this fish as I have not heard of any others breeding it.
I strongly recommend that Rasbora vulcanus be kept and propagated by aquarists because it is one of the more colorful and attractive rasboras that I know of, and a great addition to the hobby. Such an active, peaceful, easy to keep, and colorful fish should not be passed by!
Pair of Volcano Rasboras