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Warm Water Marine Fish (Seabass, Sea bream, Barramundi, Yellowtail)

What’s important for warm water marine fish?  

  • High water quality 
  • Correct water temperature 
  • Sufficient tidal movement (if cage farming) 
  • Optimal pH levels (If operating a recirculating system)
  • Sourcing strong fingerlings
  • Stable environmental conditions  
  • Optimal oxygen conditions

Common challenges 

For seabass: 

  • Slow growth: This is often due to being raised in small ponds.  
  • Spread of pathogens: Viruses, bacteria and parasites are often spread via other fish, which are being used to help cut costs. 
  • Anemia: This can be caused by leeches and contributes to lethargy and poor performance. 
  • Streptococcus bacteria: A viral infection that can affect major organs such as liver, pancreas and heart if not treated and managed correctly.

 For sea bream: 

  • Edwardsiella tardaLocal strains of this bacteria do not cause high peaks of mortality but can slowly kill fish during the cycle. A common cause is stress. Affected fish do not always die, but they cannot be harvested due to apparent injuries to the skin, eyes and head, or a noticeably “off” smell.  
  • Henneguya pagriA myxospora that affects internal organs and oxygen absorption of younger fish. 

For barramundi:

  • Iridovirus: This is the most severe disease for barramundi, causing mortality of up to 80–90%.
  • Parasites: Neobenedinia commonly affects newly stocked barramundi in open ocean cages — fish may develop skin and tail rot and mortality rates can go as high as 30–40%.
  • Streptococcus iniae: This is the most serious bacterial disease to Barramundi, causing acute mortality with a cumulative mortality of up to 70%.

For yellowtail: 

  • Lactococcus type 2: Spikes of mortality may occur, especially during the summer months.  
  • Fishmeal replacement: Yellowtail are highly carnivorous and have higher protein requirements than salmonids. 
  • Benedenia seriolae and Neobenedenia girellae (skin flukes): These parasites appear year-round but are especially prevalent during the summer months. 

Tips for maximizing health and performance 

  • Optimize feed and water quality 
  • Reduce stocking density (to prevent cannibalism and stress) 
  • Minimize stress during transportation 
  • Improve gut health 
  • Formulate stress-resistant nutrients in feed to help enhance immunity 
  • Provide proper ventilation, such as in the case of air-breathing catfish species  
  • Apply correct feeding levels (just below satiation)