Frequently asked questions (FAQs)

1. What is a typical, suitable proximate composition for the diet of European seabass?

Proximate composition (% dry feed basis)	Life stage/size class
Proximate composition (% dry feed basis)	Fry	Fingerling	Juvenile	Grower	Broodstock
Crude protein, % min	50	45–50	45-50	45	45
Crude lipid, % min	15-18
Crude fibre, % max	2	3–4	3–4	3–4	3–4
Digestible energy, min kJ/g		19	19	19	19
Protein to energy ratio, mg/kJ		25	25	25	25
Phosphorous, % min	0.8	0.8	0.8	0.8	0.8

2. What protein level and essential amino acid levels are required for European seabass diets?

Dietary protein requirement of European seabass varies at different stages of its life and they require 10 essential amino acids like any other fish species for normal growth.

Nutrient level	Life stage
Nutrient level	Fry	Fingerling	Juvenile	Grower	Broodstock
Crude protein, % min	50	45–50	45-50	45	45
Amino acids (% minimum of dietary protein)
Arginine		3.9–4.6	4.6	4.6	4.6
Histidine			1.6	1.6	1.6
Isoleucine			2.6	2.6	2.6
Leucine			4.3	4.3	4.3
Lysine		4.8	4.8	4.8	4.8
Methionine			2.3	2.3	2.3
Methionine + Cystine		4
Phenylalanine			2.6	2.6	2.6
Threonine		2.6	2.7	2.7	2.7
Tryptophan		0.5–0.7	0.6	0.6	0.6
Valine			2.9	2.9	2.9

3. What protein sources could be used in European seabass feeds and their proximate composition?

	Crude protein	Crude lipid	Ash	Phosphorus
Marine sources
Fishmeal	70.0	8–10	10–12	2.1
Krill meal	58.0	18.0	13.0
Cereals
Corn	8.0	1–3	1–2	0.3
Corn gluten meal	60.0	3.0	2.0	0.4
Wheat	12.0	1–3	17.0	0.1
Wheat gluten	78.0	2.0	0.8	0.1
Pulses
Pea	22.0	1–2	3.0	0.4
Faba bean	24.0	2.0	3.0	0.5
Lupins	34.0	8.0	3.0	0.4
Oilseeds
Rapeseed meal	38–44	1–2	3–7	1.0
Sunflower meal	35.0	4.0	8.0	0.9
Full fat soybean	36.0	19.0	6.0	0.5
Soybean meal	46–48	0,5–1	6.0	0.7
Soy protein concentrate	68.0	1.5	4.0	0.9

4. What lipid sources could be used in European seabass feeds and what is their fatty acid composition?

Marine fish oil such as menhaden, herring, mackerel, capelin, salmon, sardine and anchovy and plant oil such as palm, soya, olive and linseed are commonly used in seabass feed. Fatty acid profiles (EPA and DHA) of marine fish oils are given below:

Fatty acid	Menhaden	Herring	Mackerel	Capelin	Salmon	Sardine	Anchovy
20:5n-3 (EPA)	13	2.9	7.6	9.4	9.8	16.9	18.2
22:6n-3 (DHA)	8.2	2.7	7.7	2.7	10.4	12.9	10.9
EPA + DHA	21.2	5.6	15.3	12.1	13.2	29.8	29.1

EPA = eicasopentanoic acid; DHA= docosahexanoic acid

5. What alternative ingredients could be used in order to decrease fishmeal dependence in European seabass diets?

The following table provides a list of possible ingredients and chemical composition of practical diets developed to decrease fishmeal use in European seabass formulations:

Ingredients (% dry matter basis)	diet 1	diet 2	diet 3	diet 4	diet 5
Fishmeal (crude protein, 70%)	52.0	40.0	25.0	12.5	5.0
Corn gluten meal		8.0	20.6	21.0	20.0
Wheat gluten			5.0	16.6	23.8
Extruded wheat	19.5	6.8	2.0
Soybean meal (crude protein, 48%)	9.5	15.0	15.0	14.0	13.2
Rapeseed meal		10.0	10.0	10.0	10.0
L-Lysine			0.07	0.65	1.00
CaHPO4.2H₂0 (18% phosphorus)			0.67	2.25	3.28
Fish oil (Scandinavian)	15.9	17.1	18.6	19.9	20.7
Binder	1.0	1.0	1.0	1.0	1.0
Yttrium oxide	0.1	0.1	0.1	0.1	0.1
Mineral premix	1.0	1.0	1.0	1.0	1.0
Vitamin premix	1.0	1.0	1.0	1.0	1.0
Chemical composition (% dry matter basis)
Dry matter	90.3	89.7	89.6	89.4	89.0
Crude protein	45.0	48.3	50.4	46.9	50.7
Crude lipid	21.6	21.7	20.0	22.8	18.3
Phosphorus	1.2	1.2	0.9	0.7	0.6
Gross energy, MJ/kg	24.2	24.3	24.1	24.8	24.4

6. What alternative ingredients could be used in order to decrease fish oil dependence in European seabass diets?

The following table provides a list of possible ingredients and chemical composition of practical diets developed to decrease fish oil use in European seabass formulations:

Ingredients (% dry matter basis)	Diet A	Diet B	Diet C
Fishmeal (Scandinavian, low temperature)	40.0	40.0	40.0
Corn gluten meal	26.3	26.3	26.3
Wheat	15.2	15.2	15.2
Premixes	2.5	2.5	2.5
Anchovy oil	16.0	6.4	6.4
Rapeseed oil	0	1.6	3.8
Linseed oil	0	5.6	3.8
Palm oil	0	2.4	1.9
Proximate composition (% dry matter basis)
Dry matter	89.8	89.1	90.6
Crude protein	53.2	51.8	52.8
Crude fat	22.2	20.8	25.8
Carbohydrates	17.1	20.3	14.6
Ash	7.5	7.1	6.8

7. What could be a typical practical diet formulation for larval rearing in European seabass culture?

Ingredients	Diet 1	Diet 2
Fishmeal		55
Fish protein hydrolysate	4	11
Casein	4
Squid meal	14
Mussel meal	4
Crayfish meal	14
Fish roe	19
Egg yolk	14
Lactic yeast	4
Fish oil	5	9
Soy oil
Soy Lecithin	3	7
Marine lecithin
Starch		5
Dextrin
Vitamin mixture	5	8
Mineral mixture	4	1
Betaine		1
Zein	6

8. What is the most appropriate feeding schedule for European seabass at different stages of the life cycle?

Larval feeds are distributed using belt feeders or other specially developed feed dispensers. In cage culture operations, both hand feeding based on feeding tables provided by feed manufacturers and the use of mechanical feed distributors occurs. Commercial cage farms use hand feeding as well as automatic feeders combined with video monitoring of feeding behaviour.

Body weight (g)	Pellet size (mm)	13 °C	15 °C	17 °C	19 °C	21 °C	23 °C	25 °C	27 °C	29 °C
0.3–0.5	0.5					Ad-libitum
0.5–1.0	0.8					Ad-libitum
1.0–3	1.1	1.21	2.42	3.63	4.84	5.41	5.81	5.85	5.24	3.52
3–8	1.5	0.91	1.83	2.74	3.66	4.09	4.39	4.42	3.95	2.66
8–15	1.9	0.74	1.48	2.22	2.96	3.31	3.55	3.58	3.20	2.15
15–20	1.9	0.63	1.27	1.90	2.53	2.83	3.04	3.06	2.74	1.84
20–40	3	0.52	1.03	1.55	2.07	2.31	2.48	2.50	2.24	1.50
40–60	3	0.43	0.86	1.29	1.72	1.93	2.07	2.08	1.87	1.25
60–100	4.5	0.35	0.71	1.06	1.41	1.58	1.69	1.70	1.53	1.02
100–160	4.5	0.29	0.57	0.86	1.14	1.28	1.37	1.38	1.24	0.83
160–300	4.5	0.23	0.46	0.69	0.91	1.02	1.10	1.11	0.99	0.66
300–450	6.5	0.16	0.33	0.49	0.66	0.74	0.79	0.80	0.71	0.48
450–700	6.5	0.13	0.26	0.40	0.53	0.59	0.63	0.64	0.57	0.38
700–1 200	9	0.10	0.20	0.29	0.39	0.44	0.47	0.47	0.42	0.28