Background Aedes aegypti is a major vector of arboviruses that may be controlled on an area-wide basis using novel approaches such as Sterile Insect Technique (SIT) and Incompatible Insect Technique (IIT). Larval diet is a major factor in mass-rearing of Aedes mosquitoes for SIT and IIT programs. Therefore, current study aimed to evaluate the effects of two novel diets developed from dry fish powder on growth and development of immature stages and adult fitness-related characteristics of Ae. aegypti in Sri Lanka. Method: Three batches of 250 Ae. aegypti first instar larvae were exposed to three different larval diets as, standard dry fish powder (D1), dry fish powder meal and brewer’s yeast (D2) and International Atomic Energy Agency (IAEA) reccomanded diet (D3), separately. Morphometric and developmental parameters of 4th instar larvae, pupae and adult mosquitoes reared under different dietary treatments were measured. General Linear Model (GLM) was used for statistical analysis. Results Significant diet-based variations were observed in the head length, head width, thoracic length, thoracic width, abdominal length, abdominal width and total length (F2, 87>4.811; P < 0.05) of Ae. aegypti larvae. The highest pupation success and the larval size were observed from the larvae fed with D2 diet, while the lowest was reported from D1. All adult morphometric parameters of adult male and female Ae. aegypti mosquitoes also denoted significant dietary variations, reporting the best sized adults from D2 diet (F2, 87>3.54; P < 0.05). Further, significantly higher fecundity and male longevity were also shown by the adult Ae. aegypti (F2, 6>7.897; P < 0.01) reared under diet D2. Conclusion Based on all the growth and developmental parameters, D2 diet reported the best quality adult mosquitoes similar to the IAEA recomanded diet, while being more inexpensive. Therefore, larval diet D2 could be recomaded as the ideal diet for for mass-rearing of Ae. aegypti for IIT and SIT-based vector control in Sri Lanka.