Vs. Aquaculture Live or Prepared Feeds

Man-made... Pellets or flakes. Dry pellets the norm (uniform nutrition.) Disadvantages: rapid sinking, unless extruded. Semi-moist pellets: soft, high quality. Disadvantage: expensive!! difficult to store in bulk.

What do we use?? Manufactured fish feeds are made from a variety of ingredients: fish meal being the main one! Alternatives are always welcome. Many times it is easier to buy off the shelf. What if you’re fish are unique, or won’t eat man made diets, or they just can’t?!

What is common here? Small size Incomplete development Lack of digestive ability! Images of a tautog as it develops

Feeding Larval Fish: Plankton Culture

Phytoplankton Production Feeding Larval Fish –Cell Size 4-8 microns –Species Isochrysis galbana Chaetoceros gracilis Nannochloris sp. Chlorella sp. Pavlova lutheri

Morphology –Golden brown –Spherical with 2 flagella –3-6 µm Salinity –8-32 ppt Temperature –11-26 °C Culture media –Guillards f/2 Proximate Analysis –52% Protein –24% Carbs –29% Fat

Isochrysis galbana Morphology –Tahiti (T-Iso strain) –Golden brown –Cells spherical with 2 flagella –5-6 µm length, 2-4 µm wide Salinity –8-32 ppt Temperature – °C Culture media –Guillards f/2 Proximate Analysis –47% Protein –24% Carbs –17% Fat

Chaetoceros gracilis Morphology –Golden brown diatom –Medium-size 12 µm wide, 10.5 µm long –Cells united in chains Salinity – ppt Temperature – °C Culture media –Guillards f/2 with Si Proximate Analysis –28% Protein –23% Carbs –9% Fat

Plankton for Shellfish Broodstock and Spat –Cell Size microns –Species Tetraselmis sp. –Green Thalassiosra sp. –Diatom

Tetraselmis sp. Morphology –Ovoid green cells –14 to 23 µm L X 8 µm W –4 flagella Salinity –28-36 ppt Temperature –22-26°C Culture media –Guillards f/2 Proximate Analysis –55% Protein –18% Carbs –14% Fat

Thalassiosra sp. Morphology –Golden brown diatom –Cells united in chains –Barrel-shaped –Non-motile –4 µm Salinity – 26 – 32 ppt Temperature –22-29 °C Culture media –Guillards f/2 with Si Other characteristics

Micro Algae Culture Culture Water Sterilization Nutrient Enrichment Inoculation Cell Counts Harvest and Feeding Stock Culture

Culture Water Sources –Seawater –Saltwater wells –Prepared seawater Salinity –26-32 ppt

Sterilization Methods –Heat Pasteurization 80 C and cool naturally –Autoclave –Sodium Hypochlorite (bleach) 0.5 ml/L (10 drops) Neutralize: ml sodium thiosulfate (248 g/L) per liter –Hydrochloric acid (muriatic) 0.2 ml/L (4 drops) Neutralize: Na 2 CO g/L

Nutrient Enrichment Guillard’s f/2 –Part A and B –0.5 ml/L each part –Na 2 Si0 3 for diatoms NutrientsConc. (mg/l Seawater) NaNO 3 75 NaH 2 PO 4.H 2 O 5 Na 2 SiO 3.9H 2 O 30 Na 2 C 10 H 14 O 8 N 2.H 2 O (Na 2 EDTA) 4.36 CoCl 2.6H 2 O 0.01 CuSO 4.5H 2 O 0.01 FeCl 3.6H 2 O 3.15 MnCl 2.4H 2 O 0.18 Na 2 MoO 4.2H 2 O ZnSO 4.7H 2 O Thiamin HCl 0.1 Biotin B

Inoculation Culture vessels –1,000 ml flask –18.7 L (5 gal.) Carboy (glass) –178 L (47 gal) Transparent Tank Add enough algae to give a strong tint to the water –100, ,000/ml Lighting –Types Sunlight Fluorescent VHO fluorescent Metal halide –Highest Densities: 24/7

Cell Counts Peak Algae Density –I. Galbana million cells/ml days 2 wk stability –T. pseudonana 4 million cells/ml 3 days 5 day stability Hemacytometer –Count total in centermost 1 mm –Multiply by 10,000 –Product = number/ml Motile cells should be killed

Harvest and Feeding Algae Density –Wk 1 = 50,000 cells/ml –Wk 2+ = 100,000 cells/ml –Onset of spatting = 200,000/ml Tank cleared in 24hrs Larvae Density –5-10 larvae/ml Liters to feed = (TD x V)/CD TD = Target Density (1,000s/ml) TD = Target Density (1,000s/ml) V = Volume of larval tank (thousands of L) V = Volume of larval tank (thousands of L) CD = Cell Density (millions/ml) CD = Cell Density (millions/ml)

Harvesting and Feeding BatchBatch –Total harvest occurs once or over several days Semi-ContinuousSemi-Continuous –Works well with diatoms –Part of the algae remains in the vessel –New media is added to replenish the algae removed

Marine Fish Larval Culture Relies on zooplankton

Marine Rotifer Brachionus plicatilis Culture units –40L plastic bags –40L cone-bottomed tanks Temperature C Salinity 26 ppt

Rotifers Laboratory production –100 to 200+  m size –2-3 week life span –small size suitable as first food

Feeding Marine Fish Rotifers –Typical first food in hatchery –Feed algae or yeast –Enrichment needed

Artemia Feeding of older larvae

Artemia Preparation Brine shrimp eggs/cysts are used globally as a food for small fish. Eggs/cysts: dry=dormant for years!! Cysts can be used unhatched, but it’s risky. Can kill small fish.

Decapsulation Sometimes decapsulation is needed (remove shell): chlorine (household bleach), leaving the unhatched baby brine shrimp protected in a membrane. Besides making the harvest of the hatched brine shrimp easier, this process also: -sterilizes the eggs -higher percentage of hatching -feed unhatched eggs to fish -decapsulated eggs can be hatched later (stored in the refrigorator)

Equipment A 3-gallon container with clear sides 1 pound of brine shrimp eggs 1 gallon of non-fragranced household bleach (5% chlorine) Brine shrimp net or filter Saturated brine solution*

Procedure Soak 1 pound of eggs in 1 gallon of fresh water for 1 hour gently aerating the eggs. After soaking, add 1 gallon of non-fragranced liquid household beach (5% chlorine) and reduce aeration. Wait till eggs turn orange. Strain contents through a brine shrimp net (or filter), and rinse in fresh water. Store in saline solution for up to a month.

Use of copepods...

Larval rearing systems are often labor intensive. Skilled workers are needed to maintain larval food culture. Sometimes special equipment or systems are needed for small fish.