Finfish Breeding and Hatchery Management

Unit 8 - Breeding of trouts

8.5. Hatching

• Eggs incubated undisturbed until the eyed-stage, in hatching troughs, vertical incubators or hatching jars.
• Hatching and rearing troughs are 40-50 cm wide, 20 cm deep and up to 4 m in length.
• Two layers of eggs are placed in wire baskets or screened trays.
• Water flow rate is 3-4 l/minute.
• As the eggs hatch, the fry drop through the mesh to a bottom trough.
• Some times up to 16 trays are stacked one above the other.
• Hatching period is 100 days at 3.9⁰C or 21 days at 14.4⁰C.
• Dead eggs are periodically removed to limit fungal attack.
• Fugal infection is controlled using formalin (37% solution of formaldehyde) for 15 minutes.
• Hatching rate is up to 95%.
• Yolk-sac absorption period lasts for 2-4 weeks.
• After hatching, the trays are removed and trough water depth is maintained at 8-10 cm until swim-up stage
• After yolk-sac absorption, the fry actively actively search for feed.
  

Developing Trout eggs