anal fin

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anal fin

n
(Zoology) a median ventral unpaired fin, situated between the anus and the tail fin in fishes, that helps to maintain stable equilibrium
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References in periodicals archive ?
It differs from its congeners by the following unique features in males: dorsal and anal fins pointed; oblique, chevron-shaped, blue-gray and dark red stripes in close proximity on flanks; proximal half dorsal and anal fin whitish with broad dark red elongated spots; caudal Fin with two or three transverse rows of dark red spots; pupil with anterior pointed extension.
Conspicuous black humeral spot distinctly separated from verticals through origins of dorsal and anal fins by 5-8 and 3-5 rows of scales, respectively.
Nape scaled, belly naked, scales do not extend to base of first dorsal or anal fins; 1 or 2 rows of scales at base of caudal fin.
Color expands outward to include half of the pectoral and anal fins, and the entire tail remains clear.
Fin spines, fin rays, and otoliths The entire left pectoral, left pelvic, dorsal, and anal fins were removed at the point of articulation from each of the 14 archived Gulf sturgeon.
Cirrhilabrus squirei also has different fin colouration, with terminal males lacking the bright red dorsal, caudal and anal fins of C.
The secondary dorsal fin (taller, rigid) and anal fins shorten into low profiles extending to just above the tail.
The second family, Heptapteridae, with positive scores, presented individuals with higher and proportionally more compressed bodies, anal fins with large areas and relatively larger mouths (see Figure 3).
Dorsal rays V + I,9; anal rays I,11; pectoral rays 17-18; eye diameter 2.75-2.95 in head length; interorbital width 5.15-5.55 in head length; first three dorsal spines subequal, the longest 4.2-4.9 in SL: caudal fin with three filamentous lobes, the longest 2.3-2.5 in SL; pectoral fins short, 3.9-4.15 in SL; colour when fresh lavender-grey with a midlateral yellow stripe from behind eye to middle of caudal fin; an iridescent blue rectangular mark at ventroposterior edge of eye, bordered below by a dusky-edged, yellow semicircular mark; submarginal yellow and blue bands in second dorsal and anal fins and upper and lower lobes of caudal fin; largest specimen, 21.0 mm SL.
The prejuvenile and juvenile organisms are distinguished by their body depth, the anal-fin formula, the serrated preoperculum and the base pigments in the dorsal and anal fins.
reported populations of masculinized eastern mosquitofish (Gambusia holbrooki), inhabiting streams receiving effluent from paper mills, in which the females showed modifications of the anal fins into normally male-associated gonopodium-like structures.