a) 4% of the 5760 compounds screened affected zebrafish embryos. 19% of the active compounds caused lethality. 175 compounds with detectable effects on zebrafish development were identified. b–c) The small molecules used for screening had molecular weights ranging from approx. 200 daltons to 700 daltons and had log P (partition coefficient) values ranging from −10 to +15. However, the log P of the bioactive compounds were restricted to 0 to +12. b) log P values between octanol and water of all the compounds screened plotted against their molecular weights. c) log P values of all the bioactive compounds (excluding the toxic compounds) plotted against their molecular weights.