Alternative name Cynodonichthys montium.

The terra typica of Rivulus montium is located between two rivers in the Chagres basin in Panama. These are the Rio Boqueron and the Rio Pequeni and the fishes were captured in a little trickling stream at the hillside. The discoverer was J.A. Griswold Jr. and the month the discovery took place was March 1936.

The Rivulus montium presented on the image to the right was collected by Boylan an Schonewille during the year 2002. The code for that trip became Panama (P) Boylan (B) and Schonewille (S) so PBS 2002 -field nr. 32. The fish was located between Palenque and Nombre de Dios, Panama.

The name R. montium is referring to the mountainious area the fis were living. This was the so called Serrania de San Blas, part of the inland mountain range in Central America.

The species is strongly related (or synonyme to) R. brunneus. Huber (Killi Data Online) states the species is valid but could have an alternative status as junior synonyme to R. brunneus. Etzel & Berkenkamp published a paper in 1997 in wich they redescribe the species but after Huber they did not use topotypic material for their work.

R. montium belongs to the Rivulus tenuis - superspecies that contains also R.frommi, R.fuscolineatus, R.istmensis, R.monikae, R.rubripunctatus, R.tenuis and R.villwocki.

Keeping and breeding is easy but a good cover of the aquarium is necessary because there ability to jump, even true the smallest opening, is unbelievable.

This species can, if there is enough space for them, housed in a tank with more males than one only and several females. If separated before and brought together again however, they can be very agressive to each other and fight to become dominant to others. The best way to have much offspring is to put a pair or an trio in a small tank from 10 liters with a small filter in it or with some airation. On the bottom some peat moss or dark gravel and a floating "mop" to give space for laying there eggs. The fish will, if they become a rich varity of life food, spawn during there whole adult life and produce daily between 5 to 15 eggs.

The eggs should be collected by hand and stored for about 14 days in a small container. Eggs are 1.6 mm and amber colored. It is wise, to add to the water you store the eggs in, some acryflavine to provent fungus coming up.

After hatching the young fry can eat fresh artemia nauplii without any problem. It takes 4 to 5 months to raise them to maturity. Often the number of males is far above the number of females. For some species this can become a major problem for the breeder as he has to raise many young fishes and so become able to distribute a few pairs to other hobbyists. Recent personal tests laerned that lower pH levels during the time of hatching gave a higher percentage of females. To achieve this I use some peat moss that I add to the container with the egss just before they are ready to hatch. This peat moss also is a good way to prevent eggs to become attact by fungusses.

There lifespan can be up to 3 years in captivity.

Remarks :

Max. size 8.0 cm.
Dorsal 9.0,
Anal 12.8,
D/A 8.3,
LL scale count (average)36.8
Pre- dorsal length to % SL – 75.2 %
Depth to % SL – 18.7 %

Hildebrand, S.F. 1938. A new Catalog of the Freshwaterfishes of Panama. Field Columbian Mus. Zool. Ser. (Chicago Nat. Hist. Mus. Fieldiana Zool.) Publication, 22: 319, fig. 9.