Msc zoology fourth semester Biology-of-Cultured-Fish.ppt

Science notes

1. Biology of Cultured FishBiology of Cultured Fish
Developed by the Harbor Branch ACTED staff

2. Freshwater FishFreshwater Fish
Less than 1% of the Earth is freshwater
•40% of fish are freshwater
•less than 5000 m deep
•species are a result of evolutionary
isolation and ecological adaptation
• No global species
• Two species are circumpolar

3. Marine FishMarine Fish
Earth is 71% saltwater
•60% of fish are marine
•Less evolutionary variable and
ecologically isolated
•The oceans provide much bigger space
•Many have large ranges
•7000 m deep
•130 global species Tuna
distribution
in southern
oceans

4. Where are most fish found?Where are most fish found?

5. And at what depth?And at what depth?

6. IchthyologyIchthyology
“the study of fishes”
• 25,000 living species
• 53,000 scientific names
• 200 new species each year

7. Some definitions…Some definitions…
Fish – singular and plural for a species
Fishes – refers to more than one species
Fish Fishes

8. Taxonomy – scientific classification
Systematics – the study of the
relationship among taxa; studies the
history of life
Why classify organisms?Why classify organisms?

9. How are plants and How are plants and
animals classified?animals classified?
Who? Carolus Linneaus, 1700’s, Europe
What? Developed binomial nomenclature
• Kingdom
•Phylum
•Class
•Order
•Family
•Genus
•Species
Red Snapper
Lutjanus campechanus

10. How would an aquaculturist How would an aquaculturist
classify fish?classify fish?
• Temperature
• Salinity
• Reproduction

11. TemperatureTemperature
Cold (trout, salmon)
Temp: below 15 C
Cool (catfish, striped bass)
Temp: 15 – 25 C
Warm (tilapia)
Temp: above 25 C

12. SalinitySalinity
Freshwater (< 1ppt)
Brackish water (1-15 ppt)
Saltwater (15-36 ppt)
Euryhaline – adapts to
different salinities
Stenohaline – cannot adapt
to different salinities

13. OsmoregulationOsmoregulation
•Aquatic species may be classified in terms of Aquatic species may be classified in terms of
their salinity tolerance as either:their salinity tolerance as either:
• saltwater species
• brackish water species
• freshwater species
•Salinity requirements may differ for a given Salinity requirements may differ for a given
species at different stages in its life cycle.species at different stages in its life cycle.
•Species adapted to a narrow range of Species adapted to a narrow range of
salinities are described assalinities are described as stenohaline .
•Species which are able to tolerate a wide Species which are able to tolerate a wide
range of salinities are described asrange of salinities are described as euryhaline.

14. OsmoregulationOsmoregulation
Osmosis
The net movement of a solvent across a permeable The net movement of a solvent across a permeable
membranemembrane from the side with the lower concentration from the side with the lower concentration
to the side with the higher concentration.to the side with the higher concentration.
Net Direction of Flow
More ConcentratedLess Concentrated
Solvent Solute particles
Membrane

15. OsmoregulationOsmoregulation
•For fish we can think of the body fluids as
one solution, the surrounding water as the
other solution, and the parts of the body
separating the two solutions as the
membrane.
•In most organisms the gills are the primary
membranes where osmosis occurs.

16. Osmoregulation: Marine FishOsmoregulation: Marine Fish
•The body fluids of saltwater species are
hypotonic (dilute) relative to the surrounding
water, so these species tend to lose water
to the environment.
•Osmoregulation in saltwater species
requires intake of water and excretion of
excess salts.

17. Osmoregulation: Osmoregulation:
Marine FishMarine Fish

18. Osmoregulation: Freshwater FishOsmoregulation: Freshwater Fish
•The ionic composition of the body fluids of The ionic composition of the body fluids of
freshwater species isfreshwater species is hypertonic (more (more
concentrated) to the surrounding water, so these concentrated) to the surrounding water, so these
species tend to accumulate water from the species tend to accumulate water from the
environment.environment.
•Osmoregulation in freshwater species involves Osmoregulation in freshwater species involves
excretion of water and active uptake and excretion of water and active uptake and
retention of salts.retention of salts.

19. Osmoregulation: Osmoregulation:
Freshwater FishFreshwater Fish

20. What is a fish?What is a fish?
Photograph by HBOI

21. Anatomy & PhysiologyAnatomy & Physiology
• Lives in water?
• Carnivore, Omnivore, Herbivore
• Vertebrate
• Poikilotherm “cold blooded”
• Fins
• Gills
• Senses
• Lateral line
• Scales
• Slime (mucus)
• Swim bladder “buoyancy compensator”
• External or Internal Reproduction