Ontogenetic eye development and related behavioural changes in larvae and juveniles of barramundiLates calcarifer(Bloch)

Abstract

Larvae and juveniles of barramundi Lates calcarifer (Bloch) were examined for the development of the retina, occurrence of the retinomotor response and retinal tapetum and change in eye size with age in days. The barramundi hatched with unpigmented non-functional eyes in which retinal cells had not yet differentiated into the various elements. Soon it was followed by rapid changes in the histology of the retina. Two-day-old larvae had a well-pigmented retina with area temporalis which would allow acute vision and prey attack in the nasal direction. At 10 days, rod cells and the retinal tapetum first appeared in the retina and the retinomotor response first occurred; these would allow feeding in dim light. The retinal tapetum moved in unison with the cones and the pigment epithelium during the retinomotor response. At 26 days, the horizontal cells were divided into two layers and the twin cones appeared. These changes in the eyes occurred concurrently or in anticipation of behavioural changes, such as the onset of the first feeding at 2 days, the shift of habitat from coastal waters to swamps at the notochord flexion stage at 7-15 days, the abrupt change in feeding behaviour from roving zooplanktivore to lurking predator at 25-30 days and a later shift of habitat from turbid swamps to open coastal or lake areas at the early juvenile stage.

Feeding Activity and Growth Performance of Shrimp Post Larvae Litopenaeus vannamei Under Light and Dark Condition

“…The samples were dehydrated with an ascending series of ethanol and cleared with xylene. After that, the samples were embedded in paraffin, cut into 6µm thick sections and lastly, stained with hematoxylin and eosin (Yahaya et al, 2011;Matsuda & Wilder, 2010;Mukai, 2006) before observation under light microscope (Eclipse 80 i , Nikon, Japan). …”

Visual thresholds for feeding and optimum light intensity for larval rearing of Asian seabass,Lates calcarifer(Bloch)

“…Rod cells first appear at 10 days in Asian seabass and the retinomotor response first becomes detectable at this time (Yahaya et al . ). Asian seabass eggs and early larvae occur in the coastal areas; older larvae move into mangrove swamps during metamorphosis (around 15 days old), and grow there until 20 cm TL (Moore ).…”

“…Vision in fish larvae has been much studied and it is well known that they have pure‐cone retinae until metamorphosis, when rod cells develop and the retinomotor response occurs (Blaxter & Jones ; Blaxter & Staines ; Blaxter ; Evans & Browman ). Work on vision in Asian seabass has barely started (Yahaya, Lim, Sitti Raehanah, Mukai, Anraku & Kawamura ).…”

Investigation into the Potential use of Inland Saline Groundwater for the Production of Live Feeds for Commercial Aquaculture Purposes

“…As the size of a larval fish's mouth is a major limiting factor in feeding, this uniform consistency in size becomes a considerable and desirable advantage in a live feed situation. Extra quantities of larger bodied Artemia were observed in the GW, which could potentially present issues with situations in which various instars are being offered to very small larvae, such as those produced by barramundi, Lates calcarifer, which are only 1.5mm long, and therefore require necessarily small (and preferably uniform) Artemia larvae upon which to feed [34][35][36]. This factor relates to the early observation of darker bodies and indicates that the Artemia have adapted somewhat sooner to the groundwater.…”