Lesson 2 - REVIEW OF BASIC BIOLOGICAL CHARACTERISTICS AND REQUIREMENTS OF IMPORTANT AQUACULTURE SPECIES

milkfish, tilapia, grouper, siganids, carps

fishes

tiger prawn, mudcrab, white shrimp

crustaceans

oyster, mussel

mollusks

• objectives of culture

• geographic and climatic considerations

• culture qualities of the organisms

• consumer acceptance and marketability

• cost of production

• domestic consumption versus export

Criteria for selection of species for culture

• securing and spawning of brood stock

• hatching of eggs

• growing fry to produce fingerlings

• food fish production

Breeding operation (hatchery):

• stocking and grow-out of fingerlings to marketable size

Production operation:

Fish

any of a large group of cold-blooded (poikilothermic), finned aquatic vertebrates. Fish are generally scaled and respire by passing water over gills.

Agnatha

Chondrichthyes

Osteichthyes

Three classes of fish

AGNATHA

primitive jawless fish (Ex. lampreys, hagfish)

CHONDRICHTHYES

jawed fish with cartilaginous skeletons (Ex. sharks, rays)

OSTEICHTHYES

fish with bony skeletons (Ex. catfish, tilapia, carps)

fish shape has a great bearing on ability to move through the water

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Fusiform

Attenuated

Depressed

Compressed

fish shapes

Fusiform

• Streamlined, torpedo - shaped

• Fast open water swimmers • Predators

• Move tail side to side

• Ex: Tuna, Swordfish, Shark, Striped

Bass, Salmon

Attenuated:

• Elongated shape

• Slow

• Live soft mud, sand, or under rocks

• Slither like a snake

• Ex: Eels, Sand Lance

Depressiform:

• Flattened top to bottom

• Live on the bottom

• Predators or scavengers

• Flap fins up and down, swim like a bird

• Ex: Halibut, Flounder, Skates, Rays

Compressiform:

• Compressed from side to side

• Quick bursts of speed over short distances

• Live among plants, move among narrow spaces

• Move tail side to side

• Ex: Moonfish, Butterflyfish

fins

supported by rays (soft, with spine)

Paired

Unpaired

types of fins

pectoral and pelvic

types of paired fins

dorsal, caudal, anal

types of Unpaired fins

• body temperature regulation, cell fluid maintenance

• protection

ex

epidermis, dermis (scales)

purpose of integument

• Camouflage (chromatophore)

• mate selection

• defense

purpose of color

integument

color

External anatomy of fish

cardiovascular system

respiratory system

excretory system

internal anatomy of fish

2 chambers

how many chamber in a fish's heart have

lungs and gills

parts of the respiratory system of fish

gills, kidneys, and osmoregulation

parts of the excretory system of fish

Marine fishes must conserve water, and therefore their kidneys excrete little water.

To maintain their water balance, marine fishes drink large quantities of seawater, retaining most of the water and excreting the salt

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Freshwater fishes

___ fishes tend to lose salt to the environment and must replace it.

They get some salt from their food, but the gills and skin inside the mouth actively absorb salt from water passed through the mouth.

female with ovaries and oviduct (no uterus), male (testes)

parts of the reproductive system of fish

a. external fertilization

b. internal fertilization

two types of reproductive system

oviparous

ovoviviparous

viviparous

types of gestation in fish

oviparous

egg-laying

ovoviviparous

eggs develop and hatch within the maternal body without nourishment from parent

viviparous

eggs develop within the maternal body, with nourishment from parent; live-bearer

stomach, intestines, liver, pancreas

parts of digestive system of fish

protein and lipids > carbohydrates

General fish nutrition

eyes, nostrils, taste buds, internal ears

parts of the sensory system of fish

lateral line (mechanoreceptor)

- a series of neuromasts (a cluster of hair cells):

sensory system that allows fishes to detect weak water motions and pressure gradients.

environmental information pressure, currents, sound, vibrations

- buoyancy, sound and pressure detection

purpose of swim bladder

freshwater

brackish water

saltwater

types of water environment

freshwater

specific gravity = 1.0

brackish water

specific gravity = 1.01

saltwater

specific gravity = 1.02

• nitrogenous

• fish waste product

• toxic

Ammonia

7.0 - 7.6

pH of freshwater

7.0 - 7.6

pH of brackish water

8.1 - 8.3

pH of Saltwater

• Effects: inhibits Nitrosomonas and Nitrobacter, direct health problems for fish

• Control: check bioload, remove wastes, use of calcium-rich substrate such as sodium bicarbonate (temporary)

Decreased pH effects and control

• Effects: ammonia is more toxic, direct health problems for fish

• Control: check substrates for calcium rich ones, use of peat moss, acetic acid (temporary)

Increased pH effects and control

• temperature increases

• salinity increases

oxygen solubility decreases as:

• respiratory distress in fish • inhibits Nitrosomonas and Nitrobacter

low oxygen effects:

0.7% dissolved oxygen

dissolved oxygen for water

• air : water interface

• aeration system

oxygen is replenished by

0 - 45 °C

temperature range

temperature changes should be gradual

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1 °C/ 2 minutes

temperature change should be no more than ____ in tank

2 -3 °C

temperature change should be no more than ____ between tanks

Chlorine/Chloramines

Heavy metal

toxic/ lethal to fish

• aeration and time

• sodium thiosulfate

• carbon filter

removal of Chlorine/Chloramines

• metal pipes

• metal tank frames

• metal decoration

sources of heavy metals

saltwater

extremely corrosive to metals

• "species specific"

• Intraspecies

• Interspecies

Social behaviors of fish