In the late 70s – early 80s, a heated controversy flared up on the pages of the magazine “Fisheries and Fisheries” regarding two similar Kharatsinov fish, Petitella georgiae and Hemigrammus rhodostomus. Who is who?
The aquarists’ answers to this question did not coincide, and after the discussion, each of its participants remained with his opinion. And after many years we return to this conversation again.
But we will talk about another fish-Hemigrammus bleheri, which by the time of the dispute has not yet been described.
Hemigrammus Blair (Hemigrammus bleheri Gery-Mahnert, 1984) lives in Brazil (Rio Negro basin) and Colombia (Meta, Inirida, Restepo, Vichada, Vaupes). It was first caught by Blair, in whose honor he received his name.
The length of the fish is up to 6 cm. The female is larger and fuller than the male.
The male is more intensely colored. On the anal fin he has hooks (perhaps not all individuals), which he often hooks on the net during transplants.
Fishes are peaceful, gregarious. They should be handled with care, as they are shy and during transplants, transportations can fall into shock (torpor, intermittent uncoordinated movements, darkening of the body) and die.
Eat live food, you can additionally give dry. For the maintenance is used an aquarium with a capacity of 30 liters, densely planted with plants.
Be sure to leave free space for swimming. The optimum water temperature is 23-25 ° C, hardness up to 12 ° (preferably not more than 6-7 °), pH 6.0-7.0.
Water should be clean, clear. Aeration, filtration and weekly replacement of a part of water (about a quarter of the volume) with fresh settled water are necessary.
Dilute fish is not easy. Before spawning, the producers feed well and varied. It is recommended to keep males and females separately for about a week.
To stimulate spawning, freshly prepared soft water is added, as well as water from an aquarium where fish have spawned recently (not necessarily of this species, but preferably of the same kind or at least family), raise the temperature of the water. Spawning can be a group, but it is better to set aside a pair or a female with two males.
As a spawn, use a 25-40-liter aquarium without soil, carefully disinfected and densely planted with plants. They should be well washed and located both at the bottom and below the surface (nitella, broadleaf plants, etc.). The water level is about 20 cm.
Temperature 26-27 ° С, hardness 2-5 ° (the first successful spawning took place with hardness less than 1 °, later there were cases of dilution at 7-11 °), pH 5.5-6.8. Fish spawned both in peat (which seems to be better) and in ordinary water, but more often with the addition of a few drops of Torumina.
Caviar slightly sticky. Part of it falls to the bottom and located at the bottom of the plant, part lingers on horizontal leaves (after a while the stickiness of the eggs, apparently, increases).
Fecundity of females – up to 400 eggs (sometimes even more), but usually 150-200.
After spawning, the producers are removed so that they do not eat caviar, and the aquarium is obscured. For prophylactic purposes, some methylene blue or trypaflavin is added to the water where the eggs are located; ozonized water of the same parameters as in an incubator can be supplied through an IV drip.
Depending on the conditions, the larvae hatch in a day or two. After this, it is necessary to remove the plants and lower the water level to 10 cm.
After 3-5 days, when the fry swim, they need to be given an infusorium, and from the second week – the ciliates and nauplia of Artemia, then a small Cyclops, etc.
With regular replacement of part of the water in the nursery aquarium (2-3 times a week – 1 / 4-1 / 5 part of the volume) the young grow quickly. At the age of two to three weeks, it is stained and reaches a length of about 4 cm by two months.
Fish are susceptible to plistophoresis, or “neon disease” (caused by the amoeba spore of Plistophora hyphessobryconis, parasitic in the muscles of the body and head, where grayish-whitish nodules are formed). Yu. A. Korzyukov (1979) considers the disease to be incurable and recommends destroying fish and plants, and disinfecting the aquarium and soil. Nevertheless, there are reports that even without the use of drugs, fish could be saved due to frequent water changes (J.
Close view – Petitella georgiae Gery-Boutiere, 1964, – petitella, or tetra false red-nourished. The latter name, however, is not entirely reasonable.
It was given due to the fact that until recently they did not know about the existence of the hemigramus of Blaehr and it was believed that amateurs in aquariums live a very petitella-like rhodostomus fish. or tetra blistering (Hemigrammus rhodostomus Ahl, 1929).
Recent studies have shown that this is a mistake. Rodostomus is rarely found in nature (it lives in the vicinity of the city of Belem in northern Brazil). He lives in very soft water and is not acclimatized in aquariums.
Under his name, hemigramus Blair and Petitella were imported to Europe, but in recent years, almost exclusively, hemigrammus, which, by the way, can live (and well-adapted individuals – and reproduce) in water of medium hardness.
These three types can be distinguished by the following features.
Have Hemigrammus Blair the red color extends beyond the gill cover and, in the form of a tapering wedge, reaches the part of the body under the base of the dorsal fin; there is a dark bean-shaped speck on the caudal stem both above and below; dark wedge, tapering from the caudal fin ends under the fat fin.
In Petitella, such a dark wedge extends beyond the adipose fin and only slightly does not reach the dorsal fin, the redness does not extend beyond the gill cover, and the dark bean-like spot on the caudal stem is only on top.
Rodostomus – the least colored appearance: bean-shaped specks are present both above and below, but a dark spot extending from the tail ends under them and does not reach the fat fin; the redness does not extend beyond the gill cover; moreover, it is smaller than even petitella, and it appears only under good conditions of existence.
Petitella’s homeland is Peru (the upper part of the Amazon Basin, more precisely, its tributaries are the lower reaches of the Huallaga River, the Marañón River and Hualanga near the city of Iquitos). The length of the fish is usually up to 5 cm.
The female is larger and fuller than the male. It is also a peaceful, moving schooling fish.
It feeds on live food, you can give and dry.
The aquarium is needed the same as for the hemigramus Blair, it is better to maintain a flock. Water temperature is 22-25 ° С, hardness is up to 12 ° (but better, apparently, up to 5-6 °), pH 6.0 – 7.0.
Water must be clean and clear; it should be aerated and weekly replaced to a quarter of the volume with fresh settled.
It is difficult to dilute petitella, as well as hemigrammus Blair. Mature fish become 6-8 months old.
Not every female is capable of spawning. The best results are obtained by schooling spawning, but doubles are also possible.
Spawning – from 15 liters, all-glass, thoroughly disinfected, without soil. Well-washed plants are placed in it, and preferably a protective net, as producers can eat caviar.
The water level is 15-20 centimeters, temperature 25-27 ° C, hardness up to 5 °, pH about 6.2. Water is desirable to peat, although successful cases of breeding were noted without peat.
Caviar falls to the bottom and on the plants.
After spawning, the producers are deposited, and the aquarium is darkened. Depending on the temperature and hardness of the water (possibly in combination with a certain pH value), the incubation period can last up to half a day or more.
Fry begin to swim 4-6 days after hatching. From this point on, the net and the plants are removed and the water level is reduced to 10 cm.
Fry are fed first with live dust, then with nauplii of crustaceans.
To all this, we can add that H. Blaeer, during an expedition to the tropics and subtropics of South America, discovered in Columbia, in the rivers Meta and Inirida, and other fish similar to Blaeer’s hemigramus, but not identical to him (without a red wedge from head to bottom dorsal fin). In the Rio Negru basin, he caught fish similar to petitella, but also not identical to it.
Were found and forms similar to rhodostomus.
Thus, the question of these species remains open, and it is possible that with further research the taxonomy may change.