Trigonectes balzanii
A small annual killifish from the Paraguay River basin, in Argentina, Brazil and Paraguay. It is of more interest to the aquarium hobby than to rod fishing.
Also called: peixe-anual-do-paraguai, peixe-anual
A fish of the family Rivulidae, a group of annual killifishes, freshwater and small. Reaches 16 cm. It lives in the Paraguay River basin, in Argentina, Brazil and Paraguay, from the bottom to midwater, without migrating. In Brazil, records come from Mato Grosso and Mato Grosso do Sul. Spawning happens on the bottom, and the eggs take five to seven months to hatch. It is easy to keep in an aquarium, which is why it is used in the aquarium trade. It is not a sport fish.
Essential profile. Identification, where it occurs and rules, with data from FishBase and the cited regulations. Season, time of day, technique and bait are added once we have a good source for the peixe-anual-do-paraguai.
A small fish with a tall body as an adult, a large head, a curved, slit-like mouth and small eyes. In adult males the eyes are smaller than in females. In juveniles, the head is large relative to the body. It lives only in the Paraguay basin, which helps set it apart from annual killifishes of other regions.
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Each card shows the day's index (0 to 100) and, below it, a strip with the index for each hour, from 0h to 23h. from poor to excellent.
Essential profile: the index uses a general fish model (weather, sun, moon and tide), without a season or time of day specific to this species.
It occurs in the Paraguay River basin, in Argentina, Brazil and Paraguay.
Habitat: Freshwater of the Paraguay basin, from the bottom to midwater.
native to the basins
Summary of the regulations we found, with the source for each. Rules change; before keeping or transporting fish, check with the state environmental agency.
Conservation: Not on the Brazilian national list (Ministerial Ordinance GM/MMA No. 1.667/2026).
We found no species-specific rule beyond the region's general rules.
Allowed: Subsistence fishing by riverside residents and authorized scientific fishing. Decree 15.166/2019 (art. 11, §5) allows catch and release only in February and only in the channels of the Paraguay and Paraná rivers. For the rest of the period, not even catch and release is allowed. Check the Imasul portaria for each season.
Source: Decreto estadual MS nº 15.166/2019, art. 11; IN IBAMA nº 201/2008
Allowed: All fishing modalities are prohibited in rivers, including catch and release (Law 9.096/2009, art. 19-A). Exceptions: subsistence fishing from shore (3 kg or 1 fish, no transport or sale) and scientific fishing. Law 13.159/2025 now allows licensed sport fishing in UHE/PCH hydropower reservoirs, natural lakes and border rivers, subject to a scientific study and a license from the environmental agency. We have not confirmed whether these licenses are already being issued.
It has no spines or dangerous teeth for anglers. Because it is very small, return it to the water carefully, keeping it wet.
Length-weight relationship W = a·Lb (a = 0.00661, b = 3.1; FishBase (relação peso-comprimento bayesiana, estimativa)). It's an average: a fat or lean fish can vary by 10% to 20%.
estimated weight
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Essential profile: size, length-weight, depth, countries and conservation come from FishBase and the cited regulations, and the texts were written from those sources. Season, time of day, sensitivities, technique and baits and lures are not included yet, because we did not find a good source for this species.
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