International Journal of Marine Science, 2017, Vol.7, No.19, 183-187
185
2.2 Saddleback syndrome case
The saddleback is located in the spinous part of the dorsal fin and there are 8 spines missing from the fin. The rays
in the soft part look normal. The shape of the saddleback is in a form of a shallow and wide embayment about 2
scale‟s lines above the lateral line, with 10 mm depth and 20 mm long. The anterior few scales of the lateral line
shown to be deformed otherwise no other anomalies were detected on the fish body. The radiograph image
showed that the whole 8 spines and their supporting pterygiophores were missing. The 3 supraneurals were the
only bony parts of the dorsal fin were left (Figure 2A; Figure 2B). No other internal skeletal deformities were
observed.
Figure 2 Radiograph o
A: normal, 192 mm total length; B: abnormal, 246 mm total length
3 Discussion
Hickey et al. (1977) described 4 stages of pughead deformity in teleostean fishes: normal, primary, secondary and
tertiary. The present case of pughead anomaly in
represents the secondary of Hickey et al. (1977)
system. Unlike other cases of pughead reported from several fish species (AL-Hassan, 1988; Jawad and Hosie,
2007; Jawad et al., 2014), the present case looks mild as the mouth is closed and the fish can avoid several risks as
this closure.
Although not much of bone elements were lost from the skull of
P. erythrinus
, but the deformation in the bones at
the anterior part of the cranium could consider this a severe case. The distorted 1
st
abdominal vertebra shown in
the x-ray might have been a result of the displacement of the posterior part of the skull, which in turn has a direct
effect on the brain. Since the preorbital area was reduced very much and the nasal openings were affected in this
specimen, the nasal organs and probably the olfactory nerve were lost too. 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
postcranial skeletal deformity as a result of pughead was reported in the historical case observed by Yiung (1901)
on small specimen of salmon species obtained from France.
Due to the natural closure of the mouth, the suggestions made by Hickey (1977) in that fishes with pughead
deformity may fail the ability to breath and feed, which in turn became unable to compete for obtaining food are
not apply to the present specimen. It is also seems that this deformity did not reduced survival potential and the
body of the deformed fish is 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
