International Journal of Marine Science, 2017, Vol.7, No.20, 188-199
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the small patches dispersed anteriorly from just under the spinous part of the dorsal fin and extended posteriorly to
underneath the soft part of the dorsal fin, and dorsally from base of the dorsal fin and just below the lateral line,
where one patch is present. The areas around the orbit and the ventral surface of the lower jaw showed to have
dark patches. No other anomalies were observed in the body of the fish.
3 Discussion
Six different types of fish abnormalities were investigated in the present, where it is the time to be reported for the
examined species from the Arabian Gulf in general and the Saudi Arabian waters in particular. It designed to
diagnose skeletal deformities in the specimens of studied species and found a probable connection between these
deformities and several types of environmental disturbs such as pollutants.
There is a considerable amount of literature on wild fish anomalies in the present time (Divananch et al., 1996;
Jawad et al., 2013; Jawad and Liu, 2015) that describes the causes of different deformities. They include both
genetic (Ishikawa, 1990) and epigenetic factors as a possible source of such aberrations (Fjelldal et al., 2009), as
well as environmental factors such as temperature, light, salinity, pH, low oxygen concentrations, inadequate
hydrodynamic conditions and parasites (Chatain, 1994; Gavaia et al., 2009).
The severe case of pughead deformity observed in
B. macrognathus
can be classified as the tertiary stages on the
system Hisckey et al. (1977). The present case is similar to those reported from several fish species by different
authors around the world (AL-Hassan, 1988; Jawad and Hosie, 2007; Macieira and Joyeux, 2007; Francini-Filho
and Amado-Filho, 2013; Jawad et al., 2014; Schmitt and Orth, 2015; Jawad et al., 2015; Sawayama and Takagi,
2016).
The displacement of the posterior part of the skull in this specimen might have a direct effect on the brain. Since
the preorbital area was reduced very much and the nasal openings were displaced and deformed, the nasal organs
and probably the olfactory nerve might lost. Dissection of the skull to study the brain is required to reveal the
damages that might occurred to the brain due to the pughead deformity. Similar anomaly was reported in the
historical case observed by Yung (1901) on small specimen of salmon species obtained from France.
The effect of pughead can be seen in the inability of the fish Fishes to breath and feed, which in turn became
unable to compete for obtaining food have a debilitating effect on the fish‟s ability to breathe and feed (Bortone,
1972). This hypothesis cannot apply in this case as the specimen has no obvious signs of poor health, so feeding
was obviously unrestricted. With the present state of the mouth and the presence of the strong sharp teeth, the fish
may have sort of plasticity and change in its feeding menu to fit the deformity in its mouth as other fish species do
(Maitipe and De Silva, 1985; de Moor and Bruton, 1988). Escaping from the predators was also not likely
deterred by the observed abnormality, because the body of the deformed fishes were robust inferring the ability to
have a quick move when potential predators appear.
The causes of the observed pughead anomaly in the specimen examined are unknown, but they probably arise
during early development (Cobcroft et al., 2001). The survival rate of abnormal fish, especially during the early
ontological stages in the wild, is unknown (Bueno et al., 2015). To determine the overall incidence and effect of
these abnormalities, survival throughout development, larva through adult, must be considered. Genetic and
epigenetic factors such as mutations or recombination of genes and exposure to contaminants such as cadmium,
zinc, lead, mercury could cause pughead deformity (Dahlberg, 1970; Sloof, 1982).
Koumoundouros et al. (1997a) found that gill-cover deformity was mainly caused by an inside folding of the
operculum and/or suboperculum, rarely by bone atrophy, and was frequently correlated with malformations of the
branchiostegal rays. The branchiostegal rays in the present case of
L. nebulosus
were normal. Therefore, the
suggestion of Koumoundouros et al. (1997b) cannot apply here. Operculum deformity has been shown to increase
the sensitivity to oxygen stress and a predisposition to myxobacterial infections (Paperna et al., 1980), whereas
during the larval stage their incidence has been shown to correlate negatively with the growth rate of the fish
(Koumoundouros et al., 1997b).
