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Teleostei (teleosts) > Atheriniformes (Silversides) > Bedotiidae (Madagascar rainbowfishes)
Etymology: Rheocles: Greek, rheos = stream + Greek, kles, kleis = straits; derhami: Named for Patrick de Rham, director of the Aquatic Conservation Network (Ref. 39832).
Eponymy: Dr Patrick Henri de Rham (d: 1936) is a Swiss zoologist, botanist, ichthyologist and aquarist in Lausanne, and was Expert Ecologist to the Coopération Technique Suisse. He is a Director of the Aquatic Conservation Network. (Also see Patrick and Rham) (Ref. 128868), visit book page.

Environment: milieu / climate zone / depth range / distribution range Ecology

Freshwater; pelagic. Tropical

Distribution Countries | FAO areas | Ecosystems | Occurrences | Point map | Introductions | Faunafri

Africa: Madagascar.

Size / Weight / Age

Maturity: L_m ? range ? - ? cm
Max length : 5.0 cm SL male/unsexed; (Ref. 39832)

Short description Identification keys | Morphology | Morphometrics

Dorsal spines (total): 2; Dorsal soft rays (total): 14 - 19; Anal spines: 1; Anal soft rays: 15 - 21; Vertebrae: 35 - 38. Rheocles derhami is readily distinguished from R. sikorae and R. wrightae by length of upper jaw (32-41%HL versus 46-58) and absence of black pigmentation of genital papilla, from R. pellegrini by number of gill rakers on lower limb of first arch (9-10 versus 6-7), from R. lateralis by caudal peduncle length (67.3-78.6%SL versus 84.6-96.7), and from R. alaotrensis by absence of chest and belly scales and paired predorsal scale rows (Ref. 39832). In life males normally light grey, the second dorsal, anal and caudal fins are bright silvery blue, the throat region is orange-red, light grey females are not brightly colored; preserved specimens are creamy yellow, scale rows in dorsal midline heavily pigmented and darkened (Ref. 39832).

Life cycle and mating behavior Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae

Main reference Upload your references | References | Coordinator | Collaborators

Stiassny, M.L.J. and D.M. Rodriguez, 2001. Rheocles derhami, a new species of freshwater rainbowfish (Atherinomorpha: Bedotiidae) from the Ambomboa River in northeastern Madagascar. Ichthyol. Explor. Freshwat. 12(2):97-104. (Ref. 39832)

IUCN Red List Status (Ref. 130435: Version 2024-1)

Critically Endangered (CR) (A2ac; B1ab(iii,v)); Date assessed: 21 June 2016

CITES

Not Evaluated

CMS (Ref. 116361)

Not Evaluated

Threat to humans

Harmless

Human uses

FAO - Publication: search | FishSource |

More information

Trophic ecology
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Ecology
Ecology

Population dynamics
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Max. ages / sizes
Length-weight rel.
Length-length rel.
Length-frequencies
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Life cycle
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Maturity/Gills rel.
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Distribution
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Anatomy
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Physiology
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Estimates based on models

Phylogenetic diversity index (Ref. 82804): PD₅₀ = 0.5078 [Uniqueness, from 0.5 = low to 2.0 = high].

Bayesian length-weight: a=0.01122 (0.00514 - 0.02450), b=3.04 (2.87 - 3.21), in cm total length, based on all LWR estimates for this body shape (Ref. 93245).

Trophic level (Ref. 69278): 3.2 ±0.40 se; based on food items.

Fishing Vulnerability (Ref. 59153): Low vulnerability (10 of 100).

Rheocles derhami Stiassny & Rodriguez, 2001