Advancement in spawning period of Labeo dyocheilus (McClelland, 1839) in the mid Himalayan regions by hormonal manipulation using Ovatide

Abstract

An attempt was made to advance the spawning period of Labeo dyocheilus (McClelland, 1839) by pretreatment with the synthetic gonadotropin releasing hormone analogue, Ovatide. Total 12 females and 24 males (1: 2 ratio) were used for breeding operations conducted during 30^th May to 30^th June 2016 comprising six sets. Female fishes of set I to IV were pretreated with intramuscular injection of the ovatide at the rate 0.3 ml kg^-1 body weight twice at an interval of two weeks while males were injected @ 0.1 ml kg^-1 body weight once before 15 days of induced breeding trial for achieving advance maturity and spawning during pre-spawning phase. Fishes of set V and VI were not subjected to any pretreatment with ovatide. On 30^th of June all the six breeding sets were were treated with ovatide for induced spawning. Female and males were injected at 0.7 ml kg^-1 and 0.3 ml kg^-1 of body weight, respectively and left overnight in FRP tanks for spawning. Results indicated that in sets I to IV, fishes successfully spawned and fertilised eggs were collected in morning hours whereas fishes of set V and VI failed to spawn. Fertilisation and survival rates recorded were 79-82% and 67-71%, respectively. Results indicated that treatment of ovatide during prespawning phase is beneficial for advancing the gonadal maturity, successful induced spawning and prolonging the breeding period which may play a key role in production of substantial quantity of seed of L. dyocheilus.

 Keywords: Advance spawning, Labeo dyocheilus, Mid Himalayas,  Ovatide