Comparative toxicity of Nerium indicum latex powder (NILP) was studied against two common predatory and weed fishes of different body size in laboratory condition and cemented and muddy pond. LC50 of NILP for predatory fish Channa punctatus was 2.13 mg/L, 7.80 mg/L and 19.26 mg/L to small size, middle size and large size fish respectively in laboratory condition after 24 h exposure periods. Similar trends were also observed in case of cemented and muddy ponds but doses were 1-4 times higher than laboratory conditions. Similar trend of result was also observed against weed fish Mystus mystus. No further mortality was observed beyond 24 h in all set of experiments suggested fast degradation of the toxicant in water. Key-wordsToxicity, Fish, Botanicals, Nerium indicum, Piscicidal Activity -------------------------------------------------IJLSSR----------------------------------------------INTRODUCTION One of the most important factors that adversely affect the aquaculture production is the presence of pests, predators and competitors of cultivated organisms. The predatory and weed fishes share and better utilized the cultured carp habitats as well as food also [1-2]. So, the removal of these unwanted fish population is necessary before the seed of cultured carps was added. Application of piscicides is the best method for eradication of unwanted fish population [3]. There are many kinds of piscicides of different effectiveness are used [4-5]. The chemically derived piscicides (toxaphene) are long lasting and its toxicity remains persist up to years and detoxify slowly, as its concentration reaches to level suitable for re-stocking [6]. On the other hand, the plant derived piscicides has gained unprecedented impetus because they detoxify rapidly i.e., easily biodegradable with less hazard of environmental contamination and have high piscicidal properties and safe for operator [7-9]. Access this article online Quick Response Code: Website: