Family: Characteristic (Characidae).
Subfamily: Piranha (Serrasalminae).
Genus: Metinnis (Metynnis) – in all types of conditions of detention, nutrition and reproduction are similar.
M. argenteus and M. hypsauchen are two species, commonly called the common name – Silver Dollar.
Metinnis silver (Metynnis argenteus) Ahl / Al 1923.
As a rule, it is considered the archetypal view of the Silver Dollar. ”
The scientific name translates as: the term of the genus “Metynnis” means “The plowshare is the sharp tip of the plow,” and the species name “argenteus” means “covered with silver.”
South America: Probably endemic to the waters of the River Tapajos, Brazil.
Silvery Metinnis in the wild inhabit densely overgrown aquatic vegetation tributaries of the river.
A silver dollar is an easily recognizable species of tropical fish due to its discoid body, with a shimmering silver color.
The overall shape of the body is mostly round and high, with very pronounced lateral contraction. The front of the profile of the back and abdomen is not evenly convex. Like most members of the family (including Piranha!), They have tiny scales with a small mouth and enlarged lips.
The tail fin recedes slightly, the fatty fin is long and low, and in mature males the front part of the anal fin is crescent-shaped.
Body color is mostly silver-gray, intensely iridescent. The back is slightly darker, with a greenish-blue tint.
Dorsal fin transparent with a series of small dark spots. Males that are kept in favorable conditions have a reddish edging of the caudal fin and gill cover.
Through each eye passes a narrow dark vertical strip. Like most fish, there are color variations.
The maximum standard length is 15 cm, the males are slightly smaller.
It is best to keep in groups of at least five fish. As a rule, peaceful fish for the aquarium community and can get along well with other large peaceful species.
Smaller fish can be eaten. Silver metinnis mainly occupy the middle and upper levels of the aquarium space, so it is a good idea to choose neighbors who occupy the lower level – the bottom of the aquarium to add contrast.
Large peace catfish, such as Plexostomus and Bronted catfish (Doradidae) will be a good choice.
For a group of adult fish will need a capacity of at least 180 cm x 37.5 cm x 37.5 cm – from 250 liters. Length and width are more important than height.
Teens of this species can be placed in small aquariums.
The difficulty of recreating the natural conditions for keeping this species in captivity is that they are ruthless eaters of aquatic vegetation. Most living plants in an aquarium will be the food source for this fish. You should choose the hard and hardy varieties, but they still need to be replaced regularly.
Alternatively, you can use artificial plastic or silk plants.
Silver Metinnis are shy fish, preferring slightly dimmed lighting and a dark gravel substrate. The aquarium should have a lot of open space, and shelters should be provided from the decor, which can be made with the help of submerged curtains and stones.
Creating favorable conditions in the aquarium will stimulate their self-confidence.
Silver dollars are hardy and disease resistant, so they can adapt to different water conditions in an aquarium. They need clean water, so good filtration and a moderate flow of water are important. A large external canister filter is best suited for this purpose.
Add a couple of circulators to create a suitable movement of water in the tank and maintain a high level of oxygen. With large / adult Metinnis glass heaters are not recommended. These fish are very active and can be easily broken.
Make sure the aquarium is securely closed, as the fish can jump out when they are frightened.
Temperature: 24 to 28 ° C
Stiffness: up to 10 ° DH
It is necessary to provide a large number of vegetable components in the diet, including the fit: zucchini, cucumber, peas, fresh greens and other green vegetables. Commercial foods are also recommended, such as algae chips, spirulina and vegetable flakes.
Metinnis silver will be happy to take most of the aquarium feed and will appreciate such treats as bloodworms, koretra and artemia.
Three to four times, in small portions for young, growing fish. Once or twice acceptable for larger specimens.
The male’s anal fin is more elongated and has a reddish tinge on it.
Silver Metinnis spawn a group, so you need a large aquarium for breeding. For successful spawning, it is necessary to create suitable conditions in the spawn.
Water parameters should be in a softer, more acidic range of characteristics of the species range, and the temperature rises to 28 ° C. Carrying out a water change for a little warmer, can stimulate spawning. Males acquire dark coloration when they are ready to breed, especially near the anal, caudal and dorsal fins.
The reddish color around the chest area is enhanced. The males begin to care for the females, chasing them around the aquarium, straightening and trembling with fins and the whole body next to them.
When the female is ready to breed, she begins to spawn, which is immediately fertilized by the male.
Eggs fall to the bottom of the aquarium. Silver Metinnis are not as inclined to eat their eggs as some other fish, but should still be removed when the spawning is over, it is easier to raise the fry.
The larvae hatch in about three days. As soon as the fry have used up their yolk sacs, they should first be offered tiny food, such as an infusorium.
As the fry grows, they can be transferred to the newly hatched Nauplii Artemia and powdered feed.
Up to 2,000 eggs, the spawning pair will be set aside, therefore high mortality in the litter is likely. It is recommended to discard the least developed, small and deformed fry to ensure that there is not a very large, controlled brood containing only healthy specimens. Fry quickly grow if they eat well and after 6-8 months it is already fully formed adult fish.
Reach puberty at the age of about 1 year.
Silver Metinnis can live in an aquarium for up to 10 years or more.
Metinnis silver (Metynnis argenteus) is very similar to another representative of a kind of Metynnis hypsauchen and both fish are sold under the name “Silver Dollar”. The latter species is commonly called Metinnis Plain or Ordinary, to distinguish it from its close relative. They are almost identical in terms of appearance and care / maintenance requirements.
These two species can still be distinguished, M. Hypsauchen has a black spot located just above and behind each eye.
Metinnis Ordinary (Metynnis hypsauchen) Müller Troschel, 1844.
Distinctive feature – has a black spot, located just above and behind each eye.
Apparently, it has an uneven distribution in some parts of Guyana, Brazil, Peru and Bolivia. It was recorded in the Amazon and Paraguay river basins, as well as in some northern rivers of the so-called Guyana Plateau.
All conditions of detention, nutrition and reproduction are identical with Metinnis silver.
Metinnis Silver Dollar is a common and popular fish in aquariums. They are associated with piranhas and indeed they are often mistaken for their predatory brethren. The Silver Dollar is part of the Metynnis genus, which is closely related to both the Mileus genus and the species of Mylossoma, which are often mistakenly taken or confused with each other.