Ornamental fish culture — A/L Biology

What must I remember about Ornamental fish culture?

• Ornamental aquaculture (floriculture / aquarium fish culture) is a high-value export sector in Sri Lanka, generating foreign exchange and rural employment through breeding freshwater and marine ornamental species.
• Breeding classification of freshwater ornamental fishes: Egg-layers / Oviparous (Barbs, Danios, Tetras, Goldfish, Angel fish scattering or depositing adhesive eggs on aquatic plants or gravel) versus Livebearers / Ovoviviparous (Guppies, Mollies, Platies, Swordtails where females give birth to free-swimming fry).
• Water quality management parameters: Dissolved oxygen (>5 mg/L via continuous aeration), pH (6.5-7.5 for most freshwater species), temperature (24-28°C), total ammonia nitrogen TAN (<0.02 mg/L un-ionized NH3), nitrite (<0.1 mg/L), and low nitrate.
• Live feed culture for fry development: Newly hatched fish fry with small mouth gapes require live microscopic plankton — Infusoria (ciliates), Rotifers (Brachionus), Moina / Daphnia water fleas, and freshly hatched Artemia (brine shrimp) nauplii before transitioning to formulated commercial pelleted feeds.
• Endemic ornamental fish conservation in Sri Lanka: Over-collection of wild endemic species (e.g., Puntius nigrofasciatus - Black ruby barb, Puntius titteya - Cherry barb) threatens wild populations, necessitating captive breeding protocols and strict export regulations under the Flora and Fauna Protection Ordinance.

Test yourself (1 minute)

1. Nitrogen cycle in aquarium biofiltration

   Fish excrete toxic ammonia (NH3) -> Nitrosomonas bacteria oxidize ammonia to toxic nitrite (NO2-) -> Nitrobacter bacteria oxidize nitrite to relatively harmless nitrate (NO3-); regular partial water exchanges remove accumulated nitrate.

2. Induced breeding via hypophysation

   Injecting pituitary gland extract or synthetic GnRH analogues (e.g., Ovaprim) into mature broodstock stimulates gonadal maturation and spontaneous spawning in recalcitrant egg-scattering ornamental fish.

3. Biosecurity quarantine protocol

   Newly acquired fish stock must be quarantined in isolated prophylactic tanks for 14-21 days with observation and anti-parasitic treatment (e.g., against Ichthyophthirius multifiliis - White spot disease) before introduction to main facilities.

Practise Ornamental fish culture questions today

Source: NIE G.C.E. (A/L) Biology Syllabus & Resource Book, Unit 10

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Where does Ornamental fish culture fit in the syllabus?

Year 2 · Term 3