Gross Abnormalities in Tilapia

Abstract

Thirty-one gross abnormalities that have been observed in tilapia are described: 10 fin, five eye, five jaw, four body shape, three head, two yolk sac, one operculum, and conjoined twins. Twenty-one have been described in published papers; the others were obtained from a survey. Breeding experiments revealed that three were heritable, while six were not heritable. Five could be caused by a bacterial infection, and one could be produced by a fungus. Four deformities were in offspring of males that had been injected with methyl methane sulphonate. Three were produced when sperm was treated with methyl methane sulphonate. Six were observed during sex reversal studies, and one was found following heat shock of fertilized eggs. Three were observed in polluted river water. The cause of other deformities is not known.

Does selection in a challenging environment produce Nile tilapia genotypes that can thrive in a range of production systems?

“…They were treated in the form of presence (abnormal) or absence (normal) and were coded as 0 = normal fish and 1 = morphological deformity (abnormal) fish (e.g. fin, body, operculum, eye and head deformities) 26 . Gill condition (red = 0; pale = 1 was an indicator of fish health related to parasite, bacteria or virus diseases) was recorded in all individual fish in both fresh and saline water.…”

Morphological and osteological malformations in hatchery bred redline torpedo fish, Sahyadria denisonii (Day 1865) (Cyprinidae)

“…Deformities in fishes are known to be caused as a result of environmental contaminants, scarcity of nutrients, oxygen deficiency, sudden changes in temperature, water current, mutation, inbreeding, parasitic infestation, mechanic trauma, and attack from predators (Fagbuaro 2009, Amitabh & Firoz 2010, Tave et al 2011, Malekpouri et al 2015. Numerous reports are available regarding abnormalities associated with both freshwater and marine fish species (Poynton 1987, Avyle et al 1989, Panday & Awasthi 1994, Madsean & Dalsgard 1999, Raj et al 2004, OlatunjiAkioye et al 2010, Dutta et al 2011, Jaward & Mamry 2012, Ma et al 2014, Malekpouri et al 2015.…”

A record of anopthalmia in Mystus tengara (Hamilton, 1822) from Assam

“…However, Tave and Handwerker (1998) reported that anophthalmia either can be heritable or can be caused by environmental disturbances. Tave et al (2011) reported gross abnormalities in tilapia pertaining to eye which were non-heritable and possibly produced by pathogen, heat shock or chemicals. Symptom of anopthalmia was also observed in carps when dissolved oxygen concentration decreases to 25 % of the saturation level (Anon, 1996).…”

“…A compiled bibliography of 1499 papers on fish anomalies was given by Dawson (1964Dawson ( , 1966Dawson ( , 1971 and Dawson and Heal (1976), of which 63 papers described eye abnormalities (Tave and Handwerker, 1998). Since then, many reports have been published on morphological anomalies in fishes (Kruitwagen et al, 2006;Tave et al, 2011;Saha and Saha, 2013). Species of the genus Mystus are small to medium sized catfishes, inhabiting streams, lakes, and rivers of southern and southeastern Asia.…”