Zsuzsanna Brlás-Molnár

Laos is one of the 32 landlocked developing countries (LLDCs) of the world, where isolation from the sea and the lack of a large-scale fishing industry have a direct effect on fish supply and fish consumption. Per capita fish consumption in LLDCs amounted to 5.1 kg/year in 2023, which is much lower than the world average (20.3 kg) as well as the Developing Regions average (20.0 kg). However, per capita fish consumption in Laos has reached 28.5 kg/year in 2023, representing the highest among the 32 LLDCs. Relying on the results and experiences of several decades of work in aquaculture development in Laos and taking into account the observations of local and international publications, documents and statistics included, the authors aimed at identifying the principal reasons for the elevated fish consumption in Laos from different perspectives, including that of aquaculture, as well as Lao language, culture, and religion. In this review, the authors analyzed the availability of aquatic resources, the role of fishing and aquaculture in the Lao economy and social life, market realities, as well as the importance of fish in Lao culture.

Laos is one of the 32 landlocked developing countries (LLDCs) of the world, where the isolation from the sea and the lack of a large-scale fishing industry have a direct effect on fish supply and fish consumption. Per capita fish consumption in LLDCs amounted to 4.6 kg/year in 2017, which is much lower than the world average (20.3 kg) as well as the Developing Regions average (19.4 kg). However, per capita fish consumption in Laos has reached 25.57 kg/year in 2021 representing the highest among the 32 LLDCs. Relying on the results and experiences of several decades of work in aquaculture development in Laos and taking into account the observations of local and international publications, documents and statistics included, the authors have investigated the reasons for the elevated fish consumption in Laos from different perspectives including that of aquaculture, and Lao language, culture, and religion. In this review, the authors analyzed the availability of aquatic resources, the role of fishing and aquaculture in the Lao economy and social life, market realities, as well as the importance of fish in the Lao culture.

A 7-week feeding trial was conducted with Nile tilapia juveniles with an average body weight of 143.5 ± 3.1 g in a cage system in order to test the effect of different feed additives on growth performance, antioxidant defense system, and immune status of fish. For this reason, experimental diets were formulated with inclusion of two different additives containing bioactive compounds, namely Nannochlorophsis gaditana in 3.5% (diet EXP-A) and black soldier fly larvae meal (diet EXP-I) in 3.5%, and compared with a diet supplemented with a mixture of two different commercial compounds (Yang and Syrena Boost) in 0.4% (diet EXP-S). As a negative control, a commercially available feed (Nongteng, Laos) for tilapia was selected. At the end of the feeding trial, production parameters and expression of genes related to the antioxidant defense system and innate immune response were studied. Furthermore, following the feeding, air exposure stress for 5 min was administered to the fish, and similar parameters were assessed. Results indicated that all diets promoted adequate fish growth (SGR 1.67–1.81 g day⁻¹) and feed utilization (FCR 1.29–1.57 g g⁻¹) with no significant (p < 0.05) differences in these parameters between the dietary fish groups. Expression of genes sod, cat, and gpx significantly increased in the liver samples of the EXP-A group at the end of feeding. Following air exposure, the EXP-A group maintained a significantly higher level of antioxidant-related gene expression compared to other treatments. Subsequently, gpx upregulation was observed in the EXP-S group in the post-stress stage compared to pre-stress. Based on our results, we recommend the inclusion of any of the tested additives at the evaluated doses to enhance the non-specific immune response of Nile tilapia. Additionally, Nannochloropsis gaditana at a 3.5% inclusion level can be used to further improve antioxidant defense capacity.

This research aimed to evaluate the reproductive potential of hatchery-reared (F1) pike-perch (Sander lucioperca) broodstock fed a commercial diet with low levels of long-chain polyunsaturated fatty acids (Lc-PUFA) and wild (F0) pike-perch broodstock fed forage fish. Reproductive parameters, including pseudogonadosomatic index (PGSI), egg size, latency time, hatching rate, embryo survival, and eggs’ fatty acid (FA) composition, as well as plasma sex hormone, glucose and immunoglobulin levels after hormone injection, were analyzed. The results showed low PGSI (10% in F1 vs. 14% in F0) and embryo survival (24% in F1 vs. 61% in F0) in F1 broodstock, but a satisfactory hatching rate (63% in F1 vs. 78% in F0) and larval size (4.6 mm in F1 vs. 4.7 mm in F0). A low arachidonic acid (ARA) percentage in F1 fish eggs (1.32%), along with increased immunoglobulin levels (17.31 g/L), suggests that immune system activation might have depleted the reserves of ARA in F1 fish, which is the key fatty acid for successful oocyte maturation. We assumed that the administration of more sustainable diets, based on terrestrial plant ingredients, is not inferior to higher-quality diets based on marine ingredients.