Cylindrotheca , an epipelic benthic pennate diatom, holds promise as a nutraceutical source and may be useful for aquaculture. Experiments were done on two Cylindrotheca species, Cylindrotheca fusiformis (UTEX 2084) and C. closterium , which was isolated from seawater collected offshore from Visakhapatnam, India. C. closterium was identified through microscopy and rDNA typing. Type and concentration of nutrient components in the culture medium that promoted best growth and highest lipid accumulation were identified. Lipid content was gravimetrically estimated. For relative comparison of the effects of different culture media on lipid content, we made estimations through rapid in situ screening method using Nile red staining and spectrofluori\xadmetry. The fatty acid profile of lipid was obtained through gas chromatography-mass spectroscopy. Nualgi, a commercially available micronutrient ready-mix with elements adsorbed as nanoparticles on a modified silica sol, was found to significantly boost growth in both Cylindrotheca species when used in lieu of a conventional micronutrient mix prepared from eight compounds. Among the three nitrogen sources tested – sodium nitrate (NaNO 3 ), urea, and ammonium chloride (NH 4 Cl) – best growth of C. fusiformis occurred on nitrate and urea, while NH 4 Cl was best for C. closterium . Lipid productivity was much higher in cultures supplied with NH 4 Cl for both Cylindrotheca species and compensated for lower biomass in C. fusiformis . Mixotrophy with glycerol or sodium acetate resulted in no significant increase in growth over photoautotrophy. Both Cylindrotheca species were lipid rich; lipid constituted 18–27% of dry biomass in the medium with NaNO 3 . Among total fatty acids, polyunsaturated fatty acids constituted <40%, eicosapentaenoic acid 25%, and arachidonic acid ∼8% and ∼4% in C. fusiformis and C. closterium , respectively. NH 4 Cl, phosphate, and Nualgi micronutrient ready-mix in concentrations optimal for each strain contribute to a good culture medium for Cylindrotheca .