## 4 Discussion  
### Feed Comparisons  
The commercial feed resulted in better growth of fish than the fishmeal-based and fishmeal-free feed in experiment 1. The specific reason for the difference in growth between the fishmeal-based local feeds and the commercial feed cannot be identified because the ingredient composition of the commercial feed was not made available by the feed manufacturer. One likely contributing factor was that the fishmeal purchased from the local market in Bukavu and used to formulate the local fishmeal-based feed was of low quality. Visual analysis of this local fishmeal, which was made from sun-dried small pelagic fish from the Lake Victoria such as the Mukene (also called Daaga) (_Rastrineobola argentea_) and imported from Uganda [11], showed that it was mostly made of bony, not fleshy, parts of the fish. Laboratory analysis confirmed it had 37.5% crude protein, which is lower than the conventional fishmeal (50-72% crude protein) used for most of the commercial feeds. [PERSON], et al. [18] reported that Mukene quality and corresponding crude protein content reduce (CP) from as high as 65% CP to below 30% CP due to adulteration, as the product leaves the landing sites on Lake Victoria to other points of sale including local and regional shops and stores.  
The growth of fish fed the local fish-meal free feed was the same as (for the Nyakabera strain) or better than (for the Lake Kivu strain) that fed the local fishmeal-based feed. Fish growth, FCR and CF of the fish fed the fishmeal-free formulated feed were not different from those of the other feeds. However, the fishmeal-free feed had higher PER compared with the fishmeal-based diet, suggesting that the fish used the protein contained in the local full-fat soybean (and the blood meal) available locally more efficiently compared with the local fishmeal for growth and maintenance. These results indicated that diet of the local strains of Nile tilapia can be formulated and applied locally without the need to include the fishmeal [19; 20]. This finding further demonstrated that the combination of available local ingredients can replace imported feeds or fishmeal for tilapia diets, and thus increase the sustainability of smallholder tilapia farming in rural DR Congo.  
There was no obvious reason to explain the lower survival (70.0%) of fish fed the fishmeal-free formulated feed compared with those fed the other feeds (82.5-87.0%). In fact, all survival rates observed in the experiment can be considered high, considering the small size of the fish stocked (0.8 g), as high mortality is frequently observed at this early life stage [21; 22].  
A financial assessment of the feed cost would be needed to decide which of the available feeds to use. Considering the assumptions that the costs of the ingredient sourcing and processing represent about 30% of the feed cost, the fishmeal-based and fishmeal-free diets formulated diet would cost 18% and 19% less than the commercial diet in Bukavu, which confirms the fact that the use of locally available ingredients could be a viable alternative to imported, expensive feeds and feed ingredients in DR Congo [9]. However in the consideration of quality local feed as a suitable alternative, caution should be taken to source quality ingredients, including fishmeal.