RESPIRATORY GILL SURFACE-AREA OF A FACULTATIVE AIR-BREATHING LORICARIID FISH, RHINELEPIS-STRIGOSA

The respiratory surface area of the gill in relation to body mass of t he facultative air-breathing loricariid fish rhinelepis strigosa was a nalyzed using logarithmic transformation (log Y = log a + b log W) of the equation Y = aW(b). The data revealed differences in growth patter n for each gill element. The increase in gill surface area was not iso metric with body mass (b = 0.76). The total number of secondary lamell ae (b = 0.38) and the average bilateral surface area of the secondary lamellae (b = 0.46) contributed most to the rate of development of the gill surface area (total area of the secondary lamellae) with increas e in body mass. Gill filament length (b = 0.339) was more important th an the frequency (number/mm) of secondary lamellae in determining the increase in the total number of secondary lamellae. The number of gill filaments showed the lowest b value, 0.072. Rhinelepis strigosa has a larger gill surface area than most other air-breathing fish, indicati ng that it is better adapted for breathing in water than in air.