Aquarium for Nannostomus.
Nannostomus inhabit water bodies located among dense forests with slow-flowing or standing water, where the bottom lacks calcium-bearing rocks and is covered with branches and leaves that, as they decompose, serve as a source of humic acids and tannins. Fishes belonging to this genus are characterized by an elongated, torpedo-shaped body and a small mouth. They feature a nocturnal coloration that appears in the dark. They have many color variations, which complicates classification. Brightly colored, attractive fish can serve as an ornament for any properly equipped aquarium. Nannostomus are small and non-aggressive inhabitants of the upper water layers.
Aquariums for these species should have a dark bottom shaded by floating plants. In places, there should be sparse thickets of plants, including fine-leaved ones, as the fish spawn among them, as well as floating plants, along with open swimming space. Lighting is diffused. A rather unpleasant feature of nannostomids is their agility and amazing ability to jump out of the aquarium. The cause of a jump can be fright or overcrowding. At night, these “somersaults” are just as precise and successful as during the day.
Peaceful, even timid schooling fish. It is best to keep Nannostomus in a school in a spacious aquarium with calm, not too active, appropriately sized tank mates. These can include small Characins, Cyprinids, and catfish. When kept in groups of 2-3, they become timid and hide in thickets. They stay in the middle and upper water layers. Almost all their time is spent slowly drifting right near the surface. Only towards evening do Nannostomus become lively, actively feeding on insects falling onto the water or small aquatic invertebrates.
Males often fight with each other, although they never inflict injuries. Sexually mature males arrange “knightly tournaments”. Two males approach each other, initially keeping some distance. Their coloration darkens, redness intensifies, and fins spread out. Then the males approach and press their bodies together, keeping head to head. The attacker mimics a side ram, while the opponent skillfully dodges and immediately rams back. Finally, after two or three lunges, one gives up, and they part ways. There are no fatal cases or even torn fins.
Pethia or pencilfish has a sleek, spindle-shaped body, which it keeps almost constantly at an angle of 50-60° head-up. Sometimes it seems as if it is standing, resting on the wide, black, rounded lower lobe of the caudal fin. Gathering in a school, pencilfish line up and stand motionless in one place for a long time. If one of them starts swimming, the rest of the fish follow it in a single line. They move smoothly, without jerks or rushes, using mainly only their pectoral fins, which constantly work like the wings of a hoverfly hanging in the July air. The soft rear part of the dorsal fin and the small transparent upper lobe of the tail work in the same mode. Out of fright, a pencilfish can sharply dart to the side and even make two jumps in a row.
An exceptionally smooth manner of behavior does not prevent the fish from being an agile jumper, and when necessary, it immediately takes advantage of this. It jumps if it is cramped in the container, precisely hitting the opening left by the aquarist. Before jumping, the fish curves, resembling an inverted question mark. While adult pencilfish maintain a mostly inclined position in the water, fry tend to swim vertically. Bending their tail like a hook and making no body movements, they move solely by means of their pectoral fins, occasionally tipping backward.
An indispensable condition for their maintenance must be crystal clear, peat-filtered water; soft or medium hardness is recommended. Soft, acidic, aged water enriched with peat extract and weak diffused light are required. Aeration and filtration are mandatory. Sensitive to nitrates and nitrites, regular water changes are necessary. Maintaining satisfactory water conditions is the main condition for the normal development of these fish. T 23-25°C; dH 3-10°; pH 5.5-7.5.
They prefer fine live food, taking into account the small size of their mouth and providing appropriate food: the smallest bloodworms, various small crustaceans (Cyclops, Diaptomus, Daphnia), Enchytraeids, chopped bloodworms, and even dry food. In the aquarium, they readily eat dry flake food. They take food from the bottom reluctantly. Spawning for this species is preferably group spawning, with males predominating in the group. They grow very slowly. At three months of age, the fry acquire the coloration of adult fish. They live up to 6 years.
Aquarium for catfish. Corydoras, Loricariidae, True catfishes.
