Module 3: Environmental Requirements for the Cultivation of Selected Aquaculture Species

1.3. Environmental Requirements for the Cultivation of Selected Aquaculture Species

1.3.1. Most Commonly Farmed Aquaculture Species in Türkiye

In Türkiye, many aquatic species are cultured in both freshwater and marine environments. According to national aquaculture production statistics, the species most commonly farmed in freshwater are Rainbow trout (Oncorhynchus mykiss), Trout (Salmo sp.) and Mirror carp (Cyprinus carpio) (TÜİK, 2024). The most frequently farmed marine species in Türkiye are Rainbow trout, Trout (Salmo sp.), Gilthead seabream (Sparus aurata), European seabass (Dicentrarchus labrax), Meagre (Argyrosomus regius), Tuna (Thunnus spp.) and Mussels (Mytilus spp.) (TÜİK, 2024). The data show that, in Türkiye, trout—particularly Rainbow trout—is extensively farmed both in freshwater and in marine environments (Republic of Türkiye Ministry of National Education, 2015). Table 1 presents the most commonly produced aquatic species and their quantities in inland waters of  Türkiye, and Table 2 shows the most commonly farmed species and their quantities in marine waters.

Table 1. The most commonly produced aquatic species and their quantities (tons) in inland waters of Türkiye (TÜİK, 2024).

Most Commonly Farmed Species in Inland Waters of Türkiye
Years / Species	Trout (Rainbow trout) (ton)	Trout (Salmo sp.) (ton)	Carp (ton)	Sturgeon (ton)	Tilapia (ton)	European catfish (ton)	Frog (ton)
2014	107533	450	157	17	32	–	50
2015	100411	755	206	28	12	–	43
2016	99712	1585	196	6	58	–	44
2017	101761	1944	233	13	8	8	43
2018	103192	1695	212	2	12	5	49
2019	113678	2375	203	–	6	121	43
2020	126101	1804	173	14	13	92	39
2021	134174	1558	171	–	6	84	49
2022	144347	1302	293	1	–	95	25
2023	154991	1440	216	1	–	79	31

 

Table 2. The most commonly farmed species in marine waters of Türkiye (TÜİK, 2024).

Most Commonly Farmed Species in Marine Waters of Türkiye
Years / Species	Trout (Rainbow trout) (ton)	Trout (Salmo sp.) (ton)	Sea bream (ton)	Sea bass (ton)	Meagre (ton)	Bluefin tuna (ton)	Mussel (ton)
2014	4812	798	41873	74653	3281	1136	–
2015	6187	685	51844	75164	2801	1710	3
2016	4643	1073	58254	80847	2463	3834	329
2017	4972	980	61090	99971	697	3802	489
2018	9235	375	76680	116915	1486	3571	907
2019	9411	281	99730	137419	3375	2327	4168
2020	18182	507	109749	148907	7428	4338	4037
2021	31509	45	133476	155151	5913	4952	4585
2022	45454	–	152469	156602	4771	3879	5469
2023	66055	–	154011	160802	6149	3674	8738

 

In addition, there are also native trout species farmed in Türkiye. These include:

• Salmo trutta macrostigma (Anatolian Mountain Trout)
• Salmo trutta abanticus (Abant Trout)
• Salmo trutta caspius (Aras Trout)
• Salmo trutta labrax (Black Sea Trout)
• Salmo trutta lacustris (Lake Trout) (Republic of Türkiye Ministry of National Education, 2015).

Worldwide, various trout species are also widely farmed. These include:

• Salmo salar (Atlantic Salmon)
• Salmo trutta trutta (Sea Trout)
• Salmo trutta fario (Brown Trout)
• Oncorhynchus mykiss (Rainbow Trout)
• Salvelinus fontinalis (Brook Trout)
• Salvelinus alpinus (Arctic Char)
• Salvelinus namaycush (Lake Trout) (Republic of Türkiye Ministry of National Education, 2015).

1.3.2. Trout Farming

1.3.2.1. Water Resources and Water Quality Parameters in Trout Farming

When selecting a water source for aquaculture, the seasonal flow rate and the physical and chemical properties of the water must be determined in accordance with the requirements of the species (Republic of Türkiye Ministry of National Education, 2015). Trout are suitable for farming in cold waters such as spring waters. In addition, trout can be raised in freshwater sources such as rivers, lakes, and groundwater as well as in seawater (Yılmaz Alabalık, 2025). It is stated that Rainbow trout can tolerate salinity levels of 18–20% (Republic of Türkiye Ministry of National Education, 2015). According to Article 6(b) of the Aquaculture Regulation, Annex 1-a specifies the water quality parameters required for trout farming. Table 3 presents the water quality parameters that must be ensured in trout farming.

Table 3. Water quality parameters for trout farming (Annex 1-a of the Implementation Principles Related to the Aquaculture Regulation) (T.C. Tarım ve Orman Bakanlığı, 2025a)

 

Water Quality Criteria for Trout Farming
Parameters	Grow-out Farming	Hatchery	Hard Water	Soft Water
Water Flow Rate** (L/s)
Temperature (°C)	4-18ºC	6-13ºC
Dissolved Oxygen (mg/L)	>5
pH	6.5 – 8.5
Ammonia (non-ionized) (mg/L)	0.1	0.02
Nitrate (mg/L)		0 – 40
Nitrite (mg/L)			<0.2	0.06 – 0.1
Alkalinity (as CaCO₃) (mg/L)		10 – 400
Carbonate* (mg/L)		0 – 25
Bicarbonate* (mg/L)		>100
Total Hardness* (as CaCO₃) (mg/L)		10 – 400
Calcium* (mg/L)		4 – 160
Magnesium*(mg/L)	“It is necessary for the buffer system.”
Manganese* mg/lt		0 – 0.01
Iron (total)* mg/lt		<0.5
Ferrous Ion* mg/lt		0
Ferric Ion* mg/lt		0.5
Phosphorus* mg/lt		0.1 – 3
CO₂* mg/lt		<60
Aluminium* mg/lt	<0.1
Cadmium* mg/lt		<0.003		<0.0004
Chromium* mg/lt	<0.05
Copper* mg/lt			<0.01	<0.006
Lead* mg/lt	<0.001
Zinc* mg/lt	0 – 0.1
Mercury * mg/lt	<0.00005
Nickel* mg/lt			<0.05	<0.1
H2S* mg/lt		<0
Suspended Solids mg/lt	<25	<5
Note: For trout, chloride should not exceed 50 mg/L for egg hatching and 200 mg/L for adults; turbidity should not exceed 10 JTU. * Parameters to be monitored when needed. ** A report on the minimum and maximum water flow rates and a document indicating the minimum water allocation available for the facility must be obtained from the General Directorate of State Hydraulic Works (DSİ).

 

1.3.2.2. Characteristics of Trout (Rainbow Trout)

There are many trout species cultured in aquaculture. The most commonly farmed trout species in aquaculture is the Rainbow trout (Oncorhynchus mykiss) (Republic of Türkiye Ministry of National Education, 2015). This species has an active feed intake and is easy to feed. It shows very good adaptability to environmental conditions. The general characteristics of Rainbow trout are presented in Table 4.

Table 4. Rainbow Trout Characteristics (Republic of Türkiye Ministry of National Education, 2015)

 

Rainbow Trout Characteristics
Appearance	Its body is elongated, and the abdominal area is silvery-white or yellowish in color (Yılmaz Alabalık, 2025).
Adaptation to Environmental Conditions	Shows very good adaptability. It is a cold-climate fish. It is partially tolerant to high temperatures and is easy to feed.
Water Resources Where It Can Be Farmed	Freshwater and seawater

 

1.3.3. Carp Farming

1.3.3.1. Water Resources and Water Quality Parameters in Carp Farming

Carp, which belong to the family Cyprinidae, inhabit freshwater in temperate climates (Ercan, 2009). Water temperature is critically important for fish reproduction, feeding, and metabolic activities. In carp, the optimum temperature values are 18–20 °C in hatcheries and 16–28 °C in grow-out farming. Conditions with dissolved oxygen levels of 3–5 mg/L are considered optimal for carp, and oxygen consumption varies depending on water temperature. For example, when water temperature increases from 10 °C to 30 °C, the oxygen consumption per kilogram of carp increases approximately sevenfold per hour (Ercan, 2009). According to Article 6(b) of the Aquaculture Regulation, Annex 1-b specifies the water quality parameters for carp farming. Table 5 summarizes the water quality parameters for carp farming.

Table 5. Water Quality Parameters for Carp Farming (Annex 1-b of the Implementation Principles Related to the Aquaculture Regulation) (T.C. Tarım ve Orman Bakanlığı, 2025b)

 

Water Quality Criteria for Carp Farming
Parameters	Grow-out Farming	Hatchery	Hard Water	Soft Water
Water Flow Rate (L/s)**
Temperature (°C)	16-28	18-20
Dissolved Oxygen (mg/L)		5
pH		6.5 – 8.5
Ammonia (non-ionized) (mg/L)	0.02
Nitrate (mg/L)		0.3
Nitrite (mg/L)	0.06 – 0.1
Alkalinity (as CaCO₃) (mg/L)*		50 – 400
Carbonate (mg/L)*		0 – 40
Bicarbonate (mg/L)*		75 – 100
Total Hardness (as CaCO₃) (mg/L)*		50 – 400
Calcium (mg/L)*		10 – 160
Magnesium (mg/L)*	It is necessary for the buffer system.
Manganese (mg/L)*		0 – 0.1
Phosphorus (mg/L)*		0.01 – 3
CO₂ (mg/L)*		0 – 15
Cadmium (mg/L)*			0.012
Copper (mg/L)*			0.112	0.005
Lead (mg/L)*	0.1
Zinc (mg/L)*		0 – 0.05	2.0	0.3
Nickel (mg/L)*	0.5
H2S* mg/lt		<0
Note: For carp and warm-water fish, turbidity should not exceed 25 JTU, electrical conductivity should not exceed 2000 µmho × 10⁶, BOD or organic matter should not exceed 4 mg/L, and chloride should not exceed 2000 mg/L, while SO₄ should not be less than 0.5 mg/L.   * Parameters to be monitored when needed.   ** A report on the minimum and maximum water flow rates and a document indicating the minimum water allocation available for the facility must be obtained from the General Directorate of State Hydraulic Works (DSİ).

1.3.3.2. Mirror Carp Characteristics

Mirror carp, a species of carp, is the third most produced species in Türkiye with a production exceeding 200 tons (TÜİK, 2024). As a cultured carp species, mirror carp has a high and broad dorsal region. In addition, scales are visible on both sides of its back, in the abdominal and pectoral areas, and along the dorsal fin (İBB Directorate of Agriculture and Fisheries, 2025). Table 6 presents the characteristics of mirror carp.

Table 6. Mirror Carp Characteristics

Mirror Carp Characteristics
Appearance	Scales are visible on both sides of its back, in the abdominal and pectoral areas, and along the dorsal fin.
Adaptation to Environmental Conditions	Quickly adapts to changes in water temperature (Aydın, 1984).
Water Resources Where It Can Be Farmed	Freshwater and seawater

 

1.3.4. Gilthead Seabream Characteristics

Gilthead seabream is recognized by its elliptical, laterally compressed body, white abdomen, dark gray back, and pinkish cheeks (Meat and Dairy Institution, 2025). Gilthead seabream is a species found in various regions of the world, such as the Atlantic Ocean, the Northwestern Black Sea, the Aegean Sea, and the Mediterranean Sea, and it can also be produced through aquaculture. Large temperature fluctuations are not suitable for gilthead seabream. In addition, the salinity levels that gilthead seabream can tolerate range from 10% to 40% (Republic of Türkiye Ministry of National Education, 2012). Table 7 summarizes the characteristics of gilthead seabream.

Table 7. Gilthead Seabream Characteristics

 

Gilthead Seabream Characteristics
Appearance	Gilthead seabream is recognized by its elliptical, laterally compressed body, white abdomen, dark gray back, and pinkish cheeks. Its length ranges between 20 and 35 cm.
Adaptation to Environmental Conditions	Shows good growth at an optimum temperature of 22–25 °C. It is affected by changes in temperature values.
Water Resources Where It Can Be Farmed	Atlantic Ocean, Northwestern Black Sea, Aegean Sea, Mediterranean Sea, and freshwater.

 

1.3.5. European Seabass Characteristics

The European seabass belongs to the genus Dicentrarchus (Republic of Türkiye Ministry of National Education, 2016). In Türkiye, the production of European seabass has exceeded 150,000 tons in recent years, making it one of the most widely farmed marine species (TÜİK, 2024). Table 8 presents the characteristics of European seabass.

Table 8. European Seabass Characteristics

European Seabass Characteristics
Appearance	It has a wide mouth; its back is dark brown to dark gray, its sides are silver, and in some individuals the belly is yellowish-white.
Adaptation to Environmental Conditions	Salinity range in which it can live: 5%–40%. Temperature range in which it can live: 10–25 °C.
Water Resources Where It Can Be Farmed	Freshwater (DSİ, 2025). They inhabit the Northeastern Atlantic Ocean, the Mediterranean Sea, and the Black Sea.

 

1.3.6. Meagre Characteristics

Meagre, is a species living in saltwater and is found in the Aegean, Mediterranean, and Marmara Seas (İzmir Metropolitan Municipality, 2025). Table 9 summarizes the characteristics of Meagre.

Table 9. Meagre characteristics

 

Meagre Characteristics
Appearance	The inside of its mouth is yellow. Its maximum recorded length is 230 cm and its maximum recorded weight is 103 kg.
Adaptation to Environmental Conditions	Optimum growth occurs at 22–24 °C (Bodur, 2018).
Water Resources Where It Can Be Farmed	Aegean Sea, Mediterranean Sea, and Marmara Sea.

 

1.3.7. Tuna Characteristics

Tuna is a fish species belonging to the family Thunnidae (Republic of Türkiye Ministry of National Education, 2016). It is commonly known as “ton” or “tuna” fish among the general public. Its average length ranges from approximately 40 to 200 cm, with a maximum of 300 cm (Republic of Türkiye Ministry of National Education, 2016). Tuna is a widely farmed marine species in Türkiye, with a production quantity of 3,674 tons in 2023 (TÜİK, 2024). Table 10 presents the characteristics of tuna.

Table 10. Tuna Characteristics

Tuna Characteristics
Appearance	Its average length ranges from approximately 40 to 200 cm, with a maximum of 300 cm.
Adaptation to Environmental Conditions	It is tolerant of high salinity levels up to 40% and can live in warm waters with temperatures between 12–30 °C.
Water Resources Where It Can Be Farmed	Mediterranean Sea, Aegean Sea, Marmara Sea, and Black Sea.

 

1.3.8. Mussel Characteristics

Mussels, belonging to the family Mytilidae, include different species such as Mytilus galloprovincialis, Modiolus barbatus, and Lithophaga lithophaga (Republic of Türkiye Ministry of National Education, 2016). Although environments with salinity between 18–20% provide optimum conditions for mussels, they can tolerate salinity levels up to 40%. They also have a wide tolerance range for different temperature conditions. Mussel farming can be carried out on the seabed, on poles, and on rafts (Republic of Türkiye Ministry of National Education, 2016). In Türkiye, mussels are widely produced, with a production of 8,738 tons in 2023 (TÜİK, 2024). Table 11 presents the characteristics of mussels.

Table 11. Mussel Characteristics

Mussel Characteristics
Appearance	They have a shelled and layered structure.
Adaptation to Environmental Conditions	Environments with a salinity of 18–20% provide optimal conditions for mussels. They have a wide tolerance range for living under different temperature conditions.
Water Resources Where They Can Be Farmed	Western Black Sea, southern part of the Gulf of İzmir, and freshwater.

 

1.3.9. Water Quality Criteria for Marine Aquaculture

According to Article 6(b) of the Aquaculture Regulation, Annex 1-c specifies the water quality criteria established for the farming of marine species such as gilthead seabream, European seabass, and tuna. These criteria are presented in Table 12.

Table 12. Water Quality Criteria for Marine Aquaculture (Annex 1-c of the Implementation Principles Related to the Aquaculture Regulation) (T.C. Tarım ve Orman Bakanlığı, 2025c)

 

Water Quality Criteria for Marine Aquaculture
Parameters	Gilthead Seabream	European Seabass	Tuna	Red Seabream	Turbot	Sturgeon	Shrimp	Bivalves
Oxygen (mg/L)	≥4	≥4	≥5	≥4	≥3	≥4	≥5	≥5 (%70)
Salinity (%)	5–40	5–40	12-40	15–40	10-40	0-20	15-35	10-37
Temperature (°C)	15-25	10-25	12-30	14-25	10-25	7-25	20-35	12-30
pH	6.5-8.5
Free CO₂ (mg/L)	0.1-10
Ammonia (NH₃) (mg/L)	0.02-2.5	0.02-2.5	0.02-2.5	0.02-2.5	0.01-0.06	0.01-0.02	0.01-0.02	0.01-0.02
Ammonium (mg/L)	0.05-1.5							**
Nitrite (NO₂) (mg/L)	<0.5							**
Nitrate (NO₃) (mg/L)	<40							**
Phosphate (mg/L)*	<1							**
Silicate (mg/L)*	2-5							**
Iron (mg/L)*	0.5-1							**
Sulphur (mg/L)*	<1							**
Suspended Solids (mg/L)*	5-80							**
Hydrocarbons (µg/L)*	<0.031							**
Turbidity (NTU)*	<29							**
* Parameters to be monitored when needed. ** Must comply with the criteria specified in the “Communiqué on Water Quality Standards for Shellfish Growing Waters” published in the Official Gazette dated June 2, 2008 and numbered 26894.                (Türkiye)

 

References

Aydın, F. (1984). Carp Production. Seminar on Fish Farming and Its Problems in Inland Waters, 8–9 December 1983, National Productivity Center Publications, No. 303, pp. 104–128.

Bodur, T. (2018). Determination of Some Growth Parameters in the Commercial Farming of Meagre (Argyrosomus regius, Asso 1801) in Earthen Ponds. Süleyman Demirel University Eğirdir Fisheries Faculty Journal, 14(3), 232–240.

Ercan, E. (2009). A Study on the Treatment of Wastewater in Carp (Cyprinus carpio L.) Culture Using a Biologically Integrated System. Master’s thesis, Istanbul University.

İBB, İstanbul Metropolitan Municipality Directorate of Agriculture and Fisheries. (2025, March 18). Freshwater Fish. İstanbul Metropolitan Municipality Directorate of Agriculture and Fisheries Website:  https://tarim.ibb.istanbul/tarim-ve-su-urunleri-mudurlugu/tatli-su baliklari.html#:~:text=Aynal%C4%B1%20Sazan&text=Pullar%20genellikle%20s%C4%B1rt%C4%B1n%20her%20iki,Aynal%C4%B1%20sazan%20bir%20k%C3%BClt%C3%BCr%20sazan%C4%B1d%C4%B1r.

İzmir Metropolitan Municipality. (2025, March 21). Meagre. İzmir Metropolitan Municipality – E-Transaction Center: https://eislem.izmir.bel.tr/tr/BalikHalFiyatlariDetay/1008/22

Meat and Dairy Institution. (2025, March 20). Gilthead Seabream. Meat and Dairy Institution Website: https://www.esk.gov.tr/

Republic of Türkiye Ministry of National Education. (2012). Maritime – Gilthead Seabream. Ankara: MEB.

Republic of Türkiye Ministry of National Education. (2015). Trout Farming – Maritime. Ankara: Ministry of National Education.

Republic of Türkiye Ministry of National Education. (2016). Maritime – Mussel Farming. Ankara: MEB.

T.C. Tarım ve Orman Bakanlığı. (2025a). Su ürünleri yetiştiriciliği yönetmeliğine ilişkin uygulama esasları [Annex 1-a of the Implementation Principles Related to the Aquaculture Regulation].

T.C. Tarım ve Orman Bakanlığı. (2025b). Su ürünleri yetiştiriciliği yönetmeliğine ilişkin uygulama esasları [Annex 1-b of the Implementation Principles Related to the Aquaculture Regulation].

T.C. Tarım ve Orman Bakanlığı. (2025c). Su ürünleri yetiştiriciliği yönetmeliğine ilişkin uygulama esasları [Annex 1-c of the Implementation Principles Related to the Aquaculture Regulation].

TÜİK-Turkish Statistical Institute (TURKSTAT). (2024, December 29). Fisheries, 2023. Retrieved from : https://data.tuik.gov.tr/Bulten/Index?p=Su-Urunleri-2023-53702

Yılmaz Alabalık. (2025, March 20). Rainbow Trout. Yılmaz Alabalık Website: https://yilmazalabalik.com/gokkusagi-alabaligi/