Reproduction, early development, and larval rearing of the climbing perch Anabas testudineus (Teleostei: Anabantidae) in captivity

Abstract

Induced spawning, early development, and larval rearing of the climbing perch <em>Anabas testudineus</em> were examined under captive conditions. Five female climbing perch [125.33 ± 3.27 mm standard length (SL); 70.67 ± 5.59 g body weight (BW)] were each paired with apparently mature males (108.50 ± 3.97 mm SL; 39.27 ± 4.70 g BW) and induced to spawn with 5,000 IU human chorionic gonadotropin (hCG) + 0.5 mL Ovaprim/kg BW. All hCG + Ovaprim-injected fish spawned 9 – 11 h after hormone administration but saline-injected fish (control group) failed to spawn. Mean egg production per female, fertilization and hatching rates, and larval production per female were 7,667 ± 1,313, 98.11 ± 1.63%, 61.01 ± 19.92%, and 4,435 ± 1,041, respectively. Fertilized eggs (1.52 – 1.96 mm in diameter) were almost spherical, non-adhesive, transparent, and buoyant due to a large, single oil globule (515 ± 33 µm in diameter). First cleavage appeared 30 min post-fertilization (MPF) and egg development lasted for 20 – 24 h post-fertilization (HPF) (29°C). Newly hatched climbing perch larvae [1.73 ± 0.08 mm in total length (TL)] with yolk volume (YV) and oil globule volume (OGV) of 0.545 ± 0.104 mm³ and 0.072 ± 0.013 mm³, respectively had no pigmented eyes or functional mouth parts and digestive tract, and immobile with the yolk sac pointed upward. Eyes became pigmented and both mouth and anus opened in 1 d old larvae (2.09 ± 0.04 mm TL) in preparation for exogenous feeding. Except for body depth (BD) and pre-anal length (PAL), a general increase in TL (1.73 – 3.72 mm), eye diameter (ED) (0.164 – 0.378 mm), head length (HL) (0.205 – 0.923 mm), and mouth gape (MG) size (0.308 – 0.552 mm) was observed, coinciding with yolk resorption in 7 d post-hatched larvae. Climbing perch larvae were reared at four stocking densities (25, 50, 75, 100 larvae L-1) and fed solely on live food (<em>Brachionus rotundiformis</em> from days 2 to 12 and <em>Artemia</em> nauplii from days 13 to 40) or co-fed live food and microparticulate diet (MPD) (<em>Artemia </em>nauplii from days 2 to 15 and <em>Artemia</em> + MPD from days 16 to 40). Mean survival rates at lower densities (25 – 50 larvae L^-1) were significantly higher than those reared at 75 and 100 larvae L^-1 (P &lt; 0.05). Furthermore, climbing perch larvae co-fed <em>Artemia</em> nauplii and MPD showed better survival (28.67 – 81.00%) than those fed solely on live food (24.88 – 64.00%). However, at the end of the 40 d trial period, growth parameters did not vary significantly among densities (<em>P</em> &gt; 0.05), except for the condition factor in larvae co-fed <em>Artemia</em> nauplii and MPD. Taken together, results demonstrate the effectiveness of hCG + Ovaprim for captive breeding and observations on the early development of climbing perch, and the feasibility of rearing the larvae at 25 – 50 L^-1 on a combination of <em>Artemia</em> nauplii and MPD under laboratory conditions.