ARK - Arizona Rivulin Keepers

Breeding Fundulopanchax nigerianus Jos Plateau

by Bill Edwards

I first acquired F. nigeranius from Bill Gallagher (BAKA) on March 18, 1998. Originally, I had them in a 20 gallon tank with a couple of mops. The fish flourished. I dutifully picked, incubated and raised the fry. Soon I was in the possession of lots of F. nigeranius.

More fish, more mops, more eggs, more work. Oh my!

I decided it was time to move to a less intensive arrangement. So, I set up an 80 gallon vivarium. Since I enjoy growing aquatic plants, I decided to use ®Turface¹ as a substrate. This is a clay-base material that is widely used in major league baseball as well as golf courses throughout the U.S. It has several advantages to other substrate materials. Notably,

As soon as the Vivarium was completed I put in the fish (about 10 pair). Time to kick back and relax.

I had effectively reduced my work load to feeding and making occasional water changes. I feed the fish mostly live brine shrimp, fruit flies, mosquito larvae (when available), and less frequently frozen food and flake. F. nigeranius are not picky eaters. Indeed, they act more like sharks in a feeding frenzy. I observed one male feed on a 1/2 inch cricket that was trying to escape from a hungry frog (Phylobates vittatus).

As time went by, my fish population increased to where I now have about 30 to 40 adult fish in this tank. I have never seen a juvenile, ever. The population has stabilized at this level. I've seen no noticeable increase in adult fish over the past 12 months.

There are no mops in the tank. I do not pick eggs. There are, however, lots of hiding places and plant roots. I had always assumed that would be the place they would lay their eggs, and perhaps they do. One morning, however, I have noticed one pair plowing into the substrate in a nice open area at the front of the tank. My first reaction, was "Boy, that's stupid. Those eggs will get eaten in a second."

It never dawned on me to try and harvest them. Anyway, my regular water change routine includes siphoning water into a bucket with a ®Python. Generally, I toss the water on some bamboo that grows right outside my back door. But, one day I needed some water to top off the daphnia tank outside.

I never gave it a thought. Several weeks later while harvesting some daphnia, I though I saw a fish. Sure enough, there were juvenile F. nigeranius swimming around. Remarkable since the water temperature fluctuates radically (it's in partial sun on concrete in Phoenix, Arizona). We had already reached 100 degrees Fahrenheit!

Positive I had discovered the easiest way possible to raise large numbers of nigeranius, I hurriedly e-mailed Bill Gallagher. Here is Bill's response:
"This is a variation of an old trick. One of the very finest breeders, Rosario LaCorte, uses the "gravel" method almost exclusively for Fundulopanchax, instead of peat or mops. He uses standard aquarium gravel (perhaps a little larger), they lay the eggs into the gravel, then every couple of weeks you swirl the gravel around. The eggs, being lighter, don't settle as fast, and if you swirl them in a circle, they gather in a small area at the bottom of the water column, just above the gravel, in the middle, and you can just put a standard net through that area and net out the eggs from the tank. Messy, but it works for Rosario. Not sure what he does then, either just water incubates the eggs or perhaps puts them damp peat moss, I think the former. I would be worried about abrasion of the eggs, but I know Rosario is the best, so it probably works."
What can I say. I was instantly deflated. Independent invention gathers few kudos especially when you're not first. Regardless, I'm satisfied with this method. If it works for Rosario and myself (wink), it could work for you too.

¹Turface comes in 50 lb. bags for about $8 to $12 (U.S.). Check with your local baseball club or golf course for their supplier. Be sure to rinse it thoroughly to remove dust.

²Soils with a high CEC tend to hold onto positively charged nutrients (e.g., potassium (K+), ammonium (NH4+), etc.) better than soils with a low CEC. That is good for getting nutrients out of the water column and to roots of your aquatic plants.

© 2002 Bill Edwards