Live food

Live food such as Artemia, Moina, rotifers, etc. is important for achieving the best fish growth and development during the larval stage, especially for the first few days post-hatching. Formulated starter feeds are available for larvae of striped catfish, but poor growth performance and high mortality of larvae have been observed (CAB International, 2006). Moreover, striped catfish larvae are cannibalistic in nature and therefore have to be reared in ponds to avoid mass mortality during the first week after hatching. Natural feed in ponds can be generated by good pond preparation (e.g. fertilization and/or stocking of Moina at 20–30 kg/ha prior to stocking of fish larvae; CAB International, 2006). However, many nursery farms apply a combination feeding of natural food (Moina, Artemia, etc.) with commercial soybean meal and soybean milk in the form of an emulsion or with commercial feeds (Bui et al., 2010) (Table 9).

Formulated feed

Formulated feed is used in intensive striped catfish farming in order to achieve high yields and to reach marketable size in a short culture period. The productivity of striped catfish in pond culture varies between 70 and 850 tonnes/ha/crop (Phan et al., 2009). However, this high productivity requires the use of formulated feeds to provide enough required nutrients for the fish; natural food is not important in this farming system.

The MPF is formulated from various feed ingredients which are chosen based on their availability, price and quality. MPFs are produced for different size classes – there are 6 to 19 MPF size classes depending on the manufacturer (Tables 10). The FMF is formulated from locally available and cheap ingredients such as rice bran, broken rice, trash fish, etc. In some cases vitamins, minerals and digestible enzymes are added into the diet.

Feed ingredients

Sources and quality of feed ingredients used to formulate striped catfish feeds are very diverse and include both locally produced and imported ingredients. Major feed ingredients are rice bran (different types), fishmeal, meat bone meal, blood meal, soybean meal, soybean cake, canola meal, cassava, oils, etc. (Table 7). For example, there are many kinds of fishmeal, including local fishmeals with protein levels ranging from 35 to 65 percent, and imported fish meals. The prices of feed ingredients depend on their quality and on seasonal fluctuations. Fishmeal is normally used only in small amounts (less than 10 percent in the diet, depending on fish size) in order to reduce feed cost.

Tran  et al. (2010b) found that defatted soybean meal protein could replace fishmeal protein at up to 60 percent without amino acid supplementation, or at up to 70 percent with amino acid (methionine and lysine) supplementation in formulated diets of 2–4 g striped catfish. Tran et al. (2010a) reported the digestibility of major feed ingredients for striped catfish fingerlings (Table 11).

Feed formulation

Normally, the protein level in formulated feeds is about 30–32 percent for the nursery stage (5–20 g). This value decreases with increasing fish size, the lowest value (22–26 percent) occurring at a size of >500 g. Similarly, the lipid level of the diet changes with fish size appropriate to the requirement, which varies from 4–6 percent. Two essential amino acids which are often supplemented in the feed are methionine and lysine. Different kinds of vitamin C are also used in MPF – for instance, "stay C", which is stable at high temperature has been used in extruded pellets. Furthermore, calcium and phosphorus may be added to the diets. 

The FMF usually has a low protein content. The diet is usually formulated from local ingredients such as fishmeal, trash fish, soybean meal, soybean cake, rice bran, broken rice, cassava, dry fish, etc. The formulation varies with the size of the fish (Huynh et al., 2006; Le and Huynh, 2006; Nguyen, 2011) (Table 8).

Feed additives

There is almost no research about feed additives for striped catfish. However, farmers often add useful bacteria or enzymes to increase digestibility and squid oil or marine fish oil as an attractant. They may also add a premix of vitamins (Table 12) and minerals (Table 13) for nutritional improvement of the feed. It is unnecessary to supply special attractants and binders for this fish because gelatinized carbohydrate is enough to bind components in feed and the smell resulting from gelatinization and the inclusion of animal oil in the diet is sufficient to  stimulate feeding. Preservatives such as butylated hydroxyl toluene (BHT), butylated hydroxyl anisole (BHA) or ethoxyquin may be added to MPF if it is to be stored for a long time, but are not added to FMFs because these feeds are used almost immediately.

Feeding schemes

Feeding schemes depend on the type of feed and the stock size. The feeding rates for MPF vary from 2 to 5 percent according to the stock size, while the feeding rate for the FMF is increased by about 1–2 percent as compared to MPF at the same fish weight. Normally, fish are fed MPF at 5 percent body weight when stock weigh less than 100 g or during the first two months and 2 percent for stock weighing over 800 g or during the last 1 to 2 months of the culture cycle. Besides feed quality, the feeding frequency is important to improve the feed conversion ratio (FCR) in striped catfish farming. The feeding frequencies do not differ between MPF and FMF, but multiple-feeding frequencies are applied for small-size fish. Fry and fingerlings are fed three or four times per day, while larger fish are fed one or two times per day (Table 14).

Feeding methods

The feeding method for striped catfish differs according to the feed type. MPF is usually broadcast over the pond surface from a feeding boat, while FMF is fed at the feeding place or station. In addition, Duong, Le and Nguyen (2010) reported that fish growth and FRC can also be improved by applying novel feeding strategies such as restricted feeding regimes and alternative feeding regimes. The growth rates of fish fed on a restricted feeding regime in which the fish were fed for seven days and subsequently starved for three days was not significantly different to that seen in fish that were fed on a continuous basis (p>0.05). Furthermore, the FCR of  fish that had been placed under a restricted feeding regime was reduced by 18 percent. Besides, the growth rate of striped catfish fed alternative feeding regimes of 30 percent MPF for seven days and 18 percent MPF for three or five days was not significantly different from that of fish that were fed 30 percent MPF all of the time (p>0.05).