The study was carried out in Asinge village off the Tororo-Malaba highway at the Aquaculture Geossy fish farm 633222.19˚E 71866.65˚N UTM 36N zone in Tororo district in the Eastern Uganda from April to May 2019.

Mono sex female juvenile catfish used for the study were obtained from the National Fisheries Resources Research Institute Entebbe. A total of 30 fishes were acclimatized without food for 3 days prior to the commencement of the feeding trial at the farm. At the end of the 3 days of acclimation period, juvenile fish of mean weight 327 g were randomly distributed into groups of 10 in 3 circular cemented tanks of 4 cubic meter capacity. The experimental set up was supplied with water through a flow system and oxygen was augmented with a one horsepower aerator. Fecal wastes and feed remnants were removed daily by siphoning using a vacuum pump. Water changes were done during sampling days.

The ingredients to be used were submitted to the college of Agriculture and Environmental Sciences, Makerere University for determination of crude protein content and it was found to be 43.2% for the soybean meal, 61.37% for Rastrineobola argetea (fish meal), 10.48% for the maize bran and 12.71% for the Geossy farm feeds (feed treatment C) which was the control. Ingredients were weighed following calculations of Pearson square method using a CP of 46.1%. The control feed was a farm formulated whose records stated that 100 kg contained 25 kg of wheat pollard, 35 kg of bread waste, 40 kg of Rastrineobola argetea and 100 g of mineral-vitamin premix.

Feed treatment (A) was composed 7.4 kg soybean (crude proteins-43.2%), 0.6 kg maize bran (crude proteins-10.48%) and 0.04 kg of mineral and vitamin premix to make an approximately 8 kg sample of 46.1% crude proteins. Feed treatment (B) was composed of 5.6 kg of Rastrineobola argetea (crude proteins-61.37%), 2.4 kg of maize bran (crude proteins-10.48%) and 0.04 kg of mineral and vitamin premix to make an approximately 8 kg sample of 46.1% crude proteins. They were uniformly mixed and warm water was added to make a dough. The material was pelleted manually using a meat-mincing machine and dried at 60˚C for 48 hours in a hot air oven. The pellets were ground into bits and stored under room temperature in labelled airtight containers.

Fish were fed a mass 5% their body weight twice a day (Ahmed et al. 2019) [31] (daily (08:00-09:00 am, 05:00-6:00 pm) throughout the week including weekends for a 30 day growth period. The standard body weight of all the fish under each of the dietary treatment was weighed fortnightly using a digital balance (0.1 g) (Ali & Jauncey, 2005) [32]. Fish were starved overnight prior to weighing. Adjustment of feed was done at the end of every weighing to feed 5% of the new body weight.

Weight Gain (WG), Specific Growth Rate (SGR), Protein Efficiency Ratio (PER), Protein Intake (PI), gonadal weight and fecundity were calculated using methods described below by Ahmed et al. (2019) [31];

Equation 1;

Weight gain ( WG ) = Final   body   weight ( g ) − Initial   body   weight ( g )

Equation 2;

Specific growth rate ( SGR ) = In ( Final   body   weight ) − In ( Initial   body   weight ) Time ( days ) × 100

Equation 3;

Protein efficiency ratio ( PER ) = Final   body   weight − Initial   body   weight Amount   of   protein   fed

Equation 4;

Gonadosomatic index ( GSI ) = Weight of ovary Weight of fish × 100

Equation 5

Fecundity = Number of eggs in subsample × Gonadweight Weight of subsample

The fish used was captured using a net from the pond. After selection, breeders were then put in separate concrete tanks filled with .well oxygenated and clean water. Only females were selected and the selection was done in the evening quickly and carefully to avoid oxygen deprivation and minimize injuries.

Brood stock management involved caring for the brood stock from the time the fish was captured and brought for breeding to the time of, stripping and return to the pond. Cleaning of the tanks, changing of the water and feeding the fish three times a day on 5% of their body weights for feed treatments A, B and C. Feeding was started 12 hours after the experimental setup to allow the fish rest. Feeding was done for four weeks.

Just prior to hormone administration on the 28^th day of the experiment, the pituitary gland was extracted from seven donor catfish (Andrus et al. 1992) [33]. The extracted pituitary gland was then placed in a micro vial and sterile double stilled water added. After grinding it using micro-pestle and more distilled water was added in order to achieve concentration of 40 mg/ml of pituitary extract and mixed thoroughly. This was then followed by centrifuging the extract for about 1 minute to separate the tissue debris from the extract. A required amount of clear supernatant was then withdrawn into a syringe and the recipient fish injected via the intramuscular route in the anterior caudal region (Haniffa & Sridhar, 2002) [34]; the fish were injected depending on weight at a dosage rate of 0.5 ml/kg body weight (Abubakar and Ipinjolu, 2019) [35]. Each was weighed before hormone administration to obtain the final weight after treatment to help calculate the weight gain. After hormone administration, each fish was put in a separate well labelled plastic can tank containing water where they stayed overnight for the latency period.

After the latency period Procedures of FAO (1994) were done with minor modifications, the fish was ready for stripping as the following signs indicated readiness for stripping; a well-rounded and soft abdomen, eggs also showed clear nucleus at the center and the genital opening was swollen and for some reddish in colour. Each fish; one at a time was then placed in a bucket, disinfected and cleaned using a towel before transferring to the stripping bowl. The fish was held at the base of the tail with the left hand by one person and the head placed using the left hand by another person with the fish belly facing down. The fish head was then slightly elevated so that the eggs flow towards the vent by gravity. The fish was then caught with the right hand and the thumb put on one side of the belly and fingers on the other side just ahead of the pelvic fins. It was then gently squeezed as the hand was being slide back towards the vent. The milking process continued until the eggs stopped flowing and the eggs were weighed.

After stripping the eggs, the eggs from each fish was weighed to get the weight of the entire egg mass from one fish, a one (1) gram sample from each egg mass was then measured separately in plastic plates (Dadebo et al. 2011) [36]. The eggs from each sample were then mixed with potassium permanganate to separate the eggs from one another in order to facilitate easy counting which was done physically. The number of eggs stripped from each fish was then calculated by multiplying the weight of the egg mass (from each female) by the number of eggs present in sampled one gram of the respective egg masses from the different fishes.

Primary data was determined from the fish, other variables were determined from the Equations (1-6) above and entered into a table (Table 1). Tukey’s multiple comparison test on weight changes, growth rates, PER, gonadal weight and fecundity in fish exposed to the three feeds was done. Graph pad prism was used to make graphs to confirm the comparisons.

The mean weight gain, specific growth rate and protein efficiency ratios were greater in group B&C and lowest in group A (Figure 1, graph 1-3). There was a significant difference in weight gains in fish on feed treatment B and A (Table 2) possibly because of the amino acid profile of feed B. There was a significant difference in weight gains in fish on feed treatment C (control) and A (Table 2) possibly because of the ingredients in wheat pollard and bread waste in C. Mean weight gain in group B was higher than in A (Figure 1, graph 1) because the diet with the highest protein leads to higher body weight gain (Degani et al. 1989) [37]. Higher weight gain in treatment B than in A could have been due to the better balance of amino acid profile and digestibility of the protein ingredient in Rastrineobola argetea and anti-nutritional remnants in soybean. This observation is in agreement with (Abdel-Warith et al. 2019 [1]; Amisah et al. 2009) [3] who reported that every time fishmeal was left out in diet formulation, it led to low weight gain. Soybean meal contains low levels of essential amino acids (methionine and lysine) resulting in poor growth and feed utilization in fish. (Yang et al. 2009) [38]. The findings agree with Goda et al. (2007) [39] about the possibility of better growth with partial replacement of fishmeal with soybean. However, the findings of the study disagree with Adewumi, (2006) [40] who proposed that heat treatment of a certain level could make soybean an absolute replacement of fish meal. Equivocally the findings disagree with Ajani et al. (2016) [41] who partially inferred that soybean can replace fish meal by 100% as protein sources and make Clarias gariepinus attain acceptable growth performance. This indicates that Soybeans can best be used in combination with Rastrineobola argetea (Goda et al. 2007) [39] and not as a sole protein source regardless of the methods of removing the anti-nutritional factors. Phytase treatment will only improve the digestibility of phosphorus (Weerd et al. 1999) [42] and this will also not make soybeans absolute fish meal replacers. Group C (control feeds) had the highest mean weight gain because it contained wheat pollard and bread waste and not maize bran as the experimental feeds. Bread waste is known to produce better growth performance compared to maize (Fakunmoju, 2014) [43].

Gonadal weight was highest in Feed C (Figure 1, graph 4), and number of eggs per gram were highest in Feed A (Figure 1, graph 5) while gonadal somatic index and fecundity were the highest in Feed C (Figure 1, graph 6-7), however, no significant differences were found for all the reproductive indices between Feeds A, B and C (Figure 1, graph 4-6). Tukey’s multiple comparison test found a significant difference in effects on gonadal weights caused by the control feed C and feed A (P = 0.0294, P < 0.05) but the results of the graph pad prism graphs were used (Table 2). However, there was only a very small difference between the mean gonadal weight in treatment C and that of treatment B. This is because increasing protein levels of the diet increase eggs size which is in agreement with (Quintero & Davis, 2016) [44]. The findings are in agreement with (Çek & Yilmaz, 2009) [45] who found that gonadal weight was increasing with the increasing energy in the feed. The studies in other geographical zones have stated that gonadal development is seasonal (Nyina-wamwiza et al. 2012 [46]; Romanova et al. 2018 [47] ) but such studies haven’t been done for Uganda; the seasonal effects on the reproductive indices are not known. The observed trend of gonadal weight is possibly the trend of n-3 fatty acids in fish as compared to soybean meal (Kubiriza et al. 2020 [48]; Mwanja et al. 2015 [18] ). Egg size is associated with higher total number of n-3 fatty acids as these fatty acids play an important structural role as components of phospholipids in fish bio-membranes (Izquierdo, 2001) [49].

There was no significant difference in the reproductive indices for the feed treatments; replacing fish meal with soybean didn’t affect mean gonadal weight, number of eggs, GSI and fecundity. The findings are in agreement with Nyina-wamwiza et al. (2012) [46] who found out that replacing fish meal didn’t affect the GSI. The findings don’t agree with (Effiong et al. 2014) [50] who found that GSI increases with increased proteins in the diet. However, the study agrees with Ahmad (2008) who found that GSI may be increased by the right balance between crude proteins and lipids as was the control feed. The low average fecundity in treatment B (677,132 eggs) is most likely to be associated with high levels of n-3 highly unsaturated fatty acids (HUFA), which was present in the fishmeal which was used as a protein source. Lipid and fatty acid composition of broodstock diet have been identified as major dietary factors that determine successful reproduction (Barua, 2011) [51]. The findings are in agreement with (Izquierdo, 2001) [49] who reported that high levels of dietary n-3 HUFA which is in fish reduce the total amount of eggs produced. Soybeans contain n-6 HUFA which increases the average fecundity as was observed in feed A (5,763,177 eggs) compared to treatment B (677,132 eggs) and the control C (1,160,546); the finding is in agreement with (Izquierdo, 2001) [47]. The findings are not in agreement with Ekanem et al. (2013) [52]; Eyo et al. (1992) [53] whose findings associated fecundity directly with weight gain and gonadal weight of fish. This was possible because feeds were a major variable in this study.