ABSTRACT
The growing demand on Oreochromis niloticus as a popular food increased interest in its aquaculture. This necessitated proper differentiation of O. niloticus from different localities to help in choosing the best specimens for brood stock production for Nile tilapia farming. Discriminant analysis was used to quantify morphometric measurements and meristic counts of O. niloticus from Kosti, Sinnar, Khashm El Girba and Al Sabloga area. Function 1 of Discriminant analysis separated O. niloticus sample from Kosti, Sinnar, and Khashm El Girba samples. Function 3 separated Kosti samples from other areas. Function 3 separated Kosti samples from other areas. Function 2 separated Kosti and Khashm El Girba samples from Sinnar and Al Sabloga samples. Discriminant analysis showed high degree of purity of O. niloticus with an overall average of 85.1%, this because the specimens from one location sharing characters with other from different location are very few. Wilks lambda analysis showed extremely highly significant difference (p<0.000) between the three functions. This analysis selected 12 morphometric characters (PP, HL, HW, IOW, AFB, CD, LAD, SNL, CPL, ED, CPD and PRP) to be used with high accuracy to discriminate between O. niloticus from the four sampling locations. Leave-one-out cross validation for O. niloticus from four locations by Discriminant analysis using 19 morphometric characters and 6 meristic counts confirmed the identity of the species.

ABSTRACT
Currently there are different types of biodigesters, which dynamizes the knowledge about the handling and construction of these models. However, the adequacy of models that will be used in experimental scale for use in research laboratories that allow better planning, execution, data collection, analysis and interpretation of the results of experiments are of fundamental importance. The objective was to manufacture a batch biodigestor prototype on an experimental scale for sample use in research. The prototypes were supplied with substrate (water and manure mix) and inoculant (ruminal biomass) and filled to 80% of the total storage capacity. The variables biogas production and pressure were evaluated. The prototype of the batch biodigestor presented satisfactory performance, producing enough pressure to move the biogas to the manometer and the gasometer, making it possible to obtain these variables.

ABSTRACT
Discriminant analysis using 19 morphometric measurements provided good separation between Oreochromis niloticus, Sarotherdon galilaeus and Coptodon zilli from Kosti area. The analysis selected lachrymal depth, head width, caudal peduncle depth, prepectoral distance and premaxillary pedical length as significant discriminant measures. Wilks lambda test indicated that the group centroids were extremely significantly different in functions1and 2, and clearly separated the three spp. Out of 12 meristic counts, the dorsal fin spine, dorsal fin rays, lateral scale, transverse line scale, anal and pectoral soft rays gave up to 80% correct separation