Case Study A

Tilapia fish farming in floating water cages is one of the fastest-growing aquaculture systems in Nigeria, particularly around the Lagos Lagoon. The lagoon provides stable water exchange, ideal temperature ranges (26–30°C), and natural plankton that supports fish growth and reduces feed costs.

The Case Study is based on 1 standard floating cage unit with partition, stocked with 1,000 tilapia juveniles, grown to market size over 5–6 months. Tilapia has high market demand in Lagos due to its mild taste, affordability, and suitability for grilling, frying, and processing.

• Increase local tilapia supply and reduce dependence on imported frozen tilapia.

• Generate steady income for participants within one production cycle.

• Utilize Lagos Lagoon sustainably through low-impact cage aquaculture.

• Produce premium-quality live tilapia for Lagos markets, restaurants, and processors.

The project uses a floating cage culture system installed in a calm area of the lagoon. This system allows us to culture tilapia in clean, oxygen-rich water while maintaining control over growth, stocking, and feeding.

3.1 Site Selection Criteria

The selected site meets the following minimum conditions:

• Water Depth: 3–5 metres, allowing free water movement under the cage.

• Current Speed: Gentle flow to bring oxygen but not enough to stress fish or damage nets.

• Accessibility: Easy to reach by boat for daily feeding, monitoring, and night checks.

• Human Activity Level: Low risk of disturbance from fishermen or boat traffic.

• Environmental Suitability: No discharge points, waste outlets, or pollution sources nearby.
  
  

3.2 Water Quality Parameters

We monitor basic water quality every week and also after heavy rain or flooding, as changes in the lagoon can affect fish health and feeding behaviour. The key indicators we track are:

• Dissolved oxygen (4–7 mg/L): Needed for healthy growth and efficient use of feed.

• Temperature (26–30°C): The ideal range for tilapia activity and appetite.

• pH level (6.5–8.5): Keeps the fish comfortable and reduces stress.

• Water transparency (30–60 cm): Helps indicate balanced algae levels and overall water condition.

If any value falls outside the ideal range, we act quickly by adjusting feeding levels, cleaning nets to improve water flow, removing debris, or adding aeration when necessary.

Field staff visit the cage daily for feeding and security checks, with additional monitoring during rainfall and tidal changes

3.3 Cage Construction and Durability

Each cage is made of:

• HDPE floating pipes (UV resistant)

• Heavy-duty netting with 10–12 mm mesh

• Anchor system to prevent drifting

• Bird and predator cover net

4.1 Stocking Strategy

We stock 1,000 healthy tilapia juveniles of 10–20 g each. Fish are sourced from certified hatcheries to reduce risk of poor-quality seed.

4.2 Stocking Density Rationale

The stocking density (~25–30 fish/m³ depending on cage size) ensures:

• Good oxygen availability

• Low stress levels

• Better survival

• Better feed conversion

This density is suitable for small-scale cage systems and promotes predictable growth. 

4.3 Feeding Schedule

Feed is given 2–3 times daily, depending on temperature and appetite. Feed size increases with fish age:

• 0.8–1.5 mm (early stage)

• 2 mm

• 3 mm

• 4 mm

• 6 mm

• 9 mm (final grow-out stage)
  
  

Feed quantity is adjusted based on body weight sampling and expected growth curves.

4.4 Sampling & Growth Monitoring

Every 2 weeks:

• 20–30 fish are collected in a scoop net

• Weight and size are recorded

• Feed adjustments are made accordingly

• Health and body condition are observed

KPIs tracked:

• Average weight gain

• Survival rate

• Feed Conversion Ratio (FCR)

These indicators help compare planned vs. actual performance. The target market size is 350–450 g per fish, depending on buyer preference.

4.5 Biosecurity Practices

• Dead fish are removed immediately and recorded.

• Hands, nets, and tools are washed before use.

• Visitors are limited around cages.

• Nets are disinfected during scheduled cleanings.

• Feeding is monitored closely to detect abnormal behaviour early.

Cost & Revenue Financial Model (Tilapia Cage – 1,000 Fish) - VIEW

Target Markets:

- Makoko fish traders.

- Ikoyi, Lekki, and Ajah restaurants.

- Local grill spots (“point & kill” joints).

- Fresh fish retailers in Bariga, Oworonshoki, and Obalende.

- Home delivery via WhatsApp and Instagram.

Marketing Actions:

- Sell live fish directly from the lagoon.

- Build partnerships with joints offering “Point & Kill Tilapia”.

- Pre-sell 40–60% of stock before harvest.

- Offer discounts for bulk purchases.

1. Water Pollution / Low Oxygen

Risk:

Lagoon pollution, runoff, or sudden oxygen drops.

Mitigation:

Place cage in low-traffic, aerated area.

Monitor dissolved oxygen (especially early morning).

Avoid overstocking.

2. Net Damage / Fish Escape

Risk:

Birds, crabs, sharp debris, boat movement.

Mitigation:

Use HDPE frames and high-quality knotless netting.

Inspect nets daily.

Install predator nets on top.

3. Predators

Risk:

Birds, reptiles, large fish.

Mitigation:

Use top netting and secure side nets.

Keep cage fully enclosed.

4. Raining Season

Risk:

Storms / Rough Water /High Water Level.

Mitigation:

Anchor cage with strong mooring ropes.

Choose protected lagoon zones.

Use wave-resistant cage design.

5. Feed Price Volatility

Risk:

Feed Price Increase.

Mitigation:

Buy feed in bulk.

Use natural plankton advantage in lagoon water.

Optimize feeding schedules.

6. Theft / Vandalism

Risk: 

Especially at night.

Mitigation:

Recruit reliable night watch/security.

Place cages in community-monitored areas.

Use padlocked feed store and tamper-proof cage designs.