- Randy Carey -
previously printed in the Jan/Feb '93 issue of the AquaNews,
a publication of the Minnesota Aquarium Society.
all rights reserved by the author and M.A.S.
Although most aquarists fail to recognize a difference among the three Rummy-Noses, these species are usually quite distinguishable from their color patterns. The following sketches illustrate these major differences.
The best scheme to differentiate the three species involves three features: the lower caudal peduncal mark, the extent of red, and the mid-body line leading into the center caudal bands. By observing the presence or absence of these three features, the aquarist should be able to determine the species. (Logically, only the first two features are needed, but the extent of red is too important to aquarist to omit from this chart.)
Differences in size, proportion, and position are easy to determine when viewing two of the different species, but difficult when looking at a tank of the same species. One should prefer keying on the features which differ by their absence or presence.
These species exhibit other visual
differences. An expert should be able to distinguish
among the three by only the caudal markings. However, this requires memory
of proportion and position. Furthermore H. bleheri differs from H.
rhodostomus by having a more rounded "snout" and a slightly deeper body
(not illustrated in the sketches).
Of course, many additional differences require closer examination, an option not readily available to the aquarist: Scale counts, dental configurations, jaw bones, et. al.
According to the Baensch Aquarium Atlas, the spawning of P. georgia has not been described and is assumed to be difficult. The Hemigrammus species have been bred, but the task is considered difficult. All sources prescribe very soft water, a pH around 6, and the inclusion of "bushy" or "fine pinnate" plants. H. rhodostomus is reportedly easier to keep and breed. Still, the Rummy-Nose has the reputation of being a difficult spawner.
The article referred to the scientific name as H. rhodostomus, an editor's note expressed the opinion that the photographed fish were the (then) newly described H. bleheri. Both of these species being very closely related, so one might assume that their spawning methods are quite similar. However, since the species are well segregated geographically, perhaps the water parameters are not the same. Given the location of bleheri (Rio Negro), I find it difficult to believe that bleheri would prefer the high 6's for spawning.
In a 1989 TFH article, Jiri Palicka offered a new element as he
described his spawning success. He believed that aquarist were having difficulty
because they assumed the Rummy-Nose spawned like most other Characidae. Rather
than scatter their eggs, they "literally hang them up" on plants just below
the surface. This is a similar behavior to that reported of some
Nannostomus (Pencilfish). Furthermore, this species spawns after dusk.
Here is how that author repeatedly bred his Rummy-Nose Tetras: 
A 7 gallon tank is covered with black plastic on three sides and on the lower part of the fourth. A fern bunch is secured (securing is important) near the uncovered side. Demineralized water is treated with peat and carefully modified with sulfates and phosphoric acid. Calcium inhibited spawning and increased mortality among the fry.
Contrary to previous suggestions, Palicka lowered the pH to only 6.6-6.7 and the temperature was a quite low 68-72 degrees. At night time a 15 watt light scatters just enough light for the fish to see the plants but not enough to find the eggs after spawning.
The male begins his flirting about a half hour after dark and spawning continues all night long. The female deposits less than five adhesive eggs each time with a night's production of 450-500. Embryos develop in 18 hours at 75 degrees. The fry can eat newly hatched brine shrimp as first food.
The following discussion refers to my specimens in '93.
Five years later I still have 3 P. georgiae. They could be the same as I can't remember ever buying replacements.
I purchased eight Petitella georgiae and placed them in 10 gallon
tank of about 80% reverse osmosis water and 20% water-softened water. I initially
added black water extract, however this species is native clear water. The
temperature is kept around 77 degrees, pH near 6.5. Within a couple of days
four of the P. georgiae died, but I have lost none since. Judging
from the size of the underbelly, I have two females and two males. With the
current water conditions little or no red shows, but the fish are lively.
In the same tank are three specimens of what I assume to be H. rhodostomus. Their caudal markings perfectly match this species, but their posterior lines are too subdued to be classic examples. Perhaps they are the undefined H. bleheri aff. Two are females and the other a male.
None of these displayed much red when I first purchased them. I cannot explain it, but while one female still shows virtually no red, the other two display a solid red confined to the head. I recently used this pair in a spawning attempt. No eggs were found, but the watersprite was clearly disturbed.
All of these fish were timid at first. After a couple of weeks of acclamation, they now swim gregariously to the tank front to greet me when I come near. Perhaps it is in anticipation of my generous feedings of baby brine shrimp twice a day.
Of course I am keeping the common H. bleheri. They are kept in a 50 gallon community comprised of mostly characins. With water that is quite soft and slightly acid, these Rummy-Noses optimally display their colors of red, black, and white--textbook specimens. Perhaps these fish are younger than those of my other species, but I find them harder to distinguish between males and females.
[addendum '98:] I recently picked up a school of the common Rummy-Noses (H. bleheri) in a trade with a wholesaler. The red was so washed out that I thought they might be rhodostomus. The wholesaler said he was losing lots so he just gave them to me.
I put them in a tank with mostly r/o water and a pH around 6. I lost only one. Within a day they were swimming actively and sporting much more red. I suspect the problem most wholesalers and stores have with Rummy-Noses and many other "delicate" tetras is that they keep them in their tap water.
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