Diamond tetra

Water parameters

Tolerated range for this species. Aim for the middle of each band rather than the extremes.

Tank and habitat

Substrate: any.

Behavior

Plant interaction: plant safe.

Feeding

Omnivore that takes essentially any food offered. Quality flake or micropellet as a staple, with frozen bloodworm, brine shrimp, daphnia, and live food (microworms, mosquito larvae) for variety. Wild fish feed on worms, small crustaceans, and insects, so a protein-leaning rotation matches natural feeding. Occasional vegetable matter (spirulina flake, blanched soft vegetables) is accepted but is not essential. The fish feeds in the midwater column and is moderately competitive at feeding time, holding its own in community tanks without dominating. Variety in diet correlates with intensity of the iridescent scaling and the dorsal-fin display in mature males. Feed twice daily.

Compatibility

• Peaceful schooling tetra (6 to 8 cm adult) that gets along with most medium community fish. Males develop long, backward-curving dorsal and anal fin extensions and intense diamond-like iridescence, and a mature group is one of the most striking tetra displays in the hobby
• Group size of six or more is essential for the species' display behaviour. In smaller groups, the iridescence-and-fin display is muted because males stop competing for female attention
• Larger and stockier than most common tetras, so handles medium community species (barbs, peaceful gouramis, smaller rainbowfish, congo tetras) without intimidation. Not appropriate with very small nano species that would be outcompeted at feeding
• Best displayed in tanks with dark substrate, subdued lighting, and tannin-stained water; bright overhead lighting on a pale substrate dulls the scale flash significantly
• May nip flowing-finned slow tankmates (angelfish, bettas, fancy guppies) in undersized groups; in a healthy group of eight or more, this rarely happens
• Excellent with corydoras and other bottom-dwellers (different tank zone), and pairs well with bristlenose pleco for algae management

Origin and habitat

A small American tetra endemic to the Lake Valencia drainage basin in north-central Venezuela. Carl H. Eigenmann described the species in 1920 as Moenkhausia pittieri from a holotype caught in the Río Tiquirito at Concejo (also written El Cosejo), in Aragua State. In 2020, Terán, Benítez, and Mirande proposed the genus Makunaima for this and several related species formerly scattered across Moenkhausia and other genera, and the species is now Makunaima pittieri. The new family placement is Acestrorhamphidae (American tetras), subfamily Megalamphodinae, following the 2020 revision; older literature places it in Characidae. The genus name Makunaima (also spelled Macunaima or Makonaima) refers to a creator god in the mythology of several Amazonian indigenous peoples; according to one version of the legend, Makunaima created the animals and a great tree from which all food plants grew. The species epithet honours Dr Henri François Pittier (1857-1950), a Swiss-born geographer, linguist, ethnographer, and botanist who moved to Costa Rica in 1887 and later did extensive natural-history work in Venezuela. In 1935 Ernst Ahl described a Para River specimen as Opisthanodus haerteli, which is now treated as a synonym of M. pittieri. Lake Valencia is the second-largest lake in Venezuela, in a basin between two mountain ranges; the lake has suffered severe pollution from agricultural and industrial runoff, recurring eutrophication and algal blooms, and a drop of nearly 60 percent in fish species diversity through the mid-to-late twentieth century. The diamond tetra is still found in shallow, well-vegetated areas of the lake and in slow-moving tributaries (Río Tiquirito, Río Vue), and the Venezuelan underwater photographer Ivan Mikolji documented a wild population near the lake in 2009. IUCN lists the species as Endangered, reflecting the deteriorating state of its only native habitat. Maximum length is around 6 cm SL; some hobby sources report up to 8 cm TL. Diagnostic features within the older Moenkhausia concept include a strongly dented maxilla, an irregular pre-dorsal line of disordered scales, ctenoid scales (rough when stroked tail-to-head) on the body, and a heavily scaled caudal fin. Wild colour shows a golden iridescent body, violet-tinged dorsal and anal fins, a yellowish caudal peduncle, and an occasional white line along the dorsal fin. Males develop notably elongated dorsal and anal fins with backward-curving tips, plus more intense scale iridescence; juveniles are dull and easily overlooked in shops until the diamond flash develops over six to twelve months. Most trade stock is mass-produced on commercial farms in Eastern Europe and the Far East rather than wild-caught.

Breeding

Egg-scatterer that breeds in home aquariums with moderate effort. Condition a pair (or a small group) for seven to ten days on live and frozen food. The breeding tank should be soft and slightly acidic (pH 6.0 to 7.0, GH under 8 dGH tolerance), dimly lit, and densely planted with fine-leaved plants (Java moss is the traditional choice) or filled with spawning mops; temperature around 26 to 27 C. Males in breeding condition display intensified iridescence and fully extended dorsal fins. Spawning typically occurs at first light, with the pair scattering 200 to 400 eggs through the plants and onto the substrate. Eggs are semi-adhesive and lightly stick to plants and spawning material. Adults eat eggs aggressively, so remove the breeding pair immediately after spawning. Eggs hatch in 24 to 36 hours at typical breeding temperatures. Fry are tiny and need infusoria-grade food for the first three to four days before graduating to baby brine shrimp. Growth is moderate; iridescent scaling begins to develop around six to eight weeks, the dorsal-fin elongation in males appears at three to four months, and full adult coloration and fin development takes well past a year. This slow maturation of the visual display is why store-bought juveniles look so different from established adults.

Common problems

The main keeping issue is not a health problem but a marketing one: juveniles in stores are small, pale, and visually unremarkable, and many buyers are disappointed expecting instant impact. The diamond flash develops gradually over six to twelve months, and the most spectacular adult colour and finnage takes well past a year. Patience pays off; few common tetras look as striking once matured. Otherwise the species is hardy. Ich appears in newly imported or freshly stressed stock; standard temperature-and-medication treatment works. Iridescent scale display loses intensity in tanks with overhead bright lighting and pale or reflective substrate; dark substrate, subdued lighting (especially with a warm-spectrum bias), and tannin-stained 'blackwater' style water produce the most striking visual effect. Water-quality tolerance is good across a moderate range of pH (roughly 5.5 to 7.5) and hardness (2 to 15 dGH). Lifespan in a properly maintained tank is five to seven years, and the most impressive scaling and fin extensions are seen on older fish. Fin nipping appears in undersized groups (fewer than six), where social tension redirects into nipping at slow long-finned tankmates; the fix is to increase the group size.

Bioload

Further reading

• Why your angelfish ate your neons