Acute toxicities of commercial grade malathion (EC50) on Esomus danricus were determined by static-with-renewal tests and found to be 0.026, 0.022, 0.02 and 0.017 mgl-1 respectively for 24, 48, 72 and 96 hours. During acute toxicity, the normal colour was found to fade, along with copious mucous secretions, irregular, erratic and jerky movements. Three sub lethal doses (0.0017, 0.00017 and 0.000017 mgl-1) were taken for determining changes in growth, somatic indices and oxygen consumption at weekly interval for 28 days. A decline in body weight accompanied by a dose and exposure dependent increase in hepato-somatic index and decline in brain and kidney-somatic indices were observed. Decline in rate of oxygen consumption in 0.0017, 0.00017 and 0.000017 mgl-1 malathion exposed fish for 7 days were 33, 28 and 10%; for 14 days were 49, 43 and 17%; for 21 days were 55, 50 and 31% and for 28 days were 69, 57 and 41% respectively.
In the anomuran crab Albunea symmista, the extent of epidermal retraction and the developmental changes of setae on the pleopods were used to define the molt cycle stages. The female crab Albunea symmista exhibits reproductive and non-reproductive molt. Hence, it shows antagonistic relationship with molting and reproduction. Thus in the case of anomuran crab Albunea symmista spawning is always followed by two successive molt. The ovary of reproductive molt remains in the spent stage. It does not undergo any further development, awaiting for the embryo development on the pleopod and hatching out from the brood at the time of the early remount stages. The ovary of non reproductive molt does not completes its maturation in the next post molt stage. As the ovarian development proceeds, the animal gets molted and it does not undergo continuous spawning in this stage. The matured ovary spawns in the late postmolt or early intermolt during reproductive molt cycle and the cycle continues.
