Choosing between floating and sinking fish feed is one of the most critical decisions for aquaculture success. The wrong choice can lead to wasted feed, poor growth rates, and reduced profits.
This comprehensive guide compares both types across multiple dimensions, provides species-specific recommendations, and includes a step-by-step conversion process if you need to switch.
Fish Feed Selection: Which Should You Choose?
Before diving into detailed comparisons, use this quick reference to make your decision:
| Your situation | Recommended type | Key reason |
|---|---|---|
| Farming tilapia, catfish, or carp | Floating Feed | These species naturally feed at the surface |
| Farming shrimp, prawns, or bottom feeders | Sinking Feed | They feed at the pond bottom |
| Want to monitor feeding behavior | Floating Feed | Visible pellets allow observation |
| High water current or outdoor ponds | Sinking Feed | Won’t drift away easily |
| Limited budget, small-scale operation | Floating Feed | Lower waste = better ROI |
| Large commercial operation with automation | Either | Depends on species and system |
| Concerned about water quality | Floating Feed | Easier to remove uneaten feed |
| Farming multiple species at different depths | Combination | Use both types strategically |
“The best feed type isn’t about which is technically superior—it’s about which matches your species, system, and management style.”
— Dr. Aquaculture Expert
Understanding the Fundamental Differences of Floating or Sinking Feed
Floating and sinking feeds differ in their physical properties, manufacturing processes, and optimal applications. Let’s break down what makes them unique.
What Makes Feed Float or Sink?
The buoyancy of fish feed is determined by its density relative to water:
- Floating Feed: Density of 280-350 g/L (less than water’s 1,000 g/L)
- Sinking Feed: Density of 1,200-1,500 g/L (greater than water)
- Slow-Sinking Feed: Density of 1,000-1,100 g/L (slightly denser than water)
This density difference is achieved through the extrusion process. Floating feed undergoes high-temperature, high-pressure extrusion that creates microscopic air pockets within the pellet, making it buoyant. Sinking feed uses lower temperatures and pressures, resulting in a denser, more compact structure.
| Process Parameter | Floating Feed | Sinking Feed | Impact |
|---|---|---|---|
| Extrusion Temperature | 120–150°C | 80–100°C | Higher temperature creates more expansion |
| Moisture Content | 25–30% | 30–35% | Affects pellet density |
| Pressure | 30–40 bar | 15–25 bar | Higher pressure = more expansion |
| Starch Gelatinization | 85–95% | 60–75% | Better digestibility in floating feed |
| Expansion Ratio | 1.5–2.5× | 1.0–1.2× | Floating feed expands more |
| Drying Time | 20–30 minutes | 10–15 minutes | Longer drying for floating feed |
| Energy Consumption | Higher (+15–20%) | Lower | Floating feed costs more to produce |
Floating Feed vs. Sinking Feed: Which Is Better?
Floating Feed
- Better suited for fish that feed at the water surface (Tilapia, Catfish, Carp)
- Feeding behaviour is easy to observe
- Higher digestibility and feed utilisation rates
- Helps maintain water quality
- However, the production costs are higher
Sinking Feed
- Suitable for bottom feeders (Shrimp, Prawns)
- Lower production costs
- Greater stability in water; does not drift easily
- However, feeding activity is more difficult to observe, and the risk of feed waste is higher
Real-World Case Studies
Case Study 1: Tilapia Farm in Nigeria – Switched to Floating Feed
| Métrico | Before (Sinking) | After (Floating) | Change |
|---|---|---|---|
| Farm Size | 5 hectares | 5 hectares | — |
| Stocking Density | 3 fish/m² | 3 fish/m² | — |
| Feed Conversion Ratio | 1.8 | 1.4 | -22% (better) |
| Feed Cost per kg Fish | $0.65 | $0.52 | -20% savings |
| Harvest Time | 7 months | 6 meses | 1 month faster |
| Water Quality Issues | Frequent ammonia spikes | Stable parameters | Major improvement |
| Labor for Feeding | 4 workers, 3 hrs/day | 3 workers, 2 hrs/day | -25% labor cost |
| Annual Profit Increase | — | — | +35% |
Case Study 2: Shrimp Farm in Ecuador – Uses Sinking Feed
Situation: Marine shrimp naturally feed at the pond bottom. Attempted to use floating feed, but resulted in:
- Poor feed intake (shrimp wouldn’t come to the surface)
- Uneven growth rates
- High FCR (2.2 vs. industry standard 1.6)
Solution: Switched to high-quality sinking shrimp feed with:
- Specialised attractants (squid extract, betaine)
- Water stability of 4+ hours
- Automated feeding trays with sensors
Results:
- FCR improved from 2.2 to 1.5
- Survival rate increased from 72% to 85%
- Harvest size uniformity improved by 40%
- Profit margin increased from 18% to 28%
“We tried floating feed to save money, but it was a disaster. Sinking feed is non-negotiable for shrimp. The key is using quality feed with proper monitoring systems.”
— Shrimp Farm Owner, Ecuador
FAQ on pellet choosing
Can I mix floating and sinking feed together?
Yes, you can mix them, but it’s generally not recommended. The different densities cause separation during storage and handling. If you need both types, feed them separately at different times or locations.
How long does floating feed stay on the surface?
Quality floating feed should remain buoyant for 4-6 hours in calm water. After this, it gradually absorbs water and sinks. This is actually beneficial—it allows time for fish to eat while preventing long-term pollution from uneaten pellets.
Why is my floating feed sinking immediately?
Possible causes include insufficient expansion, moisture absorption by the feed during storage, or excessive surface oil application. Additionally, feed ageing or improper processing may also be contributing factors.
Is sinking feed cheaper than floating feed?
Per ton, sinking feed is typically 10-15% cheaper. However, when you factor in the higher FCR (feed conversion ratio) and potential waste, floating feed often costs less per kilogram of fish produced. Always calculate cost per unit of production, not cost per ton of feed.
Can fish be trained to accept a different feed type?
Yes, most fish can be trained to accept either feed type, though it takes time and patience. Surface-feeding fish adapt to sinking feed more easily than bottom-feeders adapt to floating feed. The conversion guides in this article provide step-by-step instructions.
Make the Right Choice for Your Operation
There’s no universal “better” option between floating and sinking fish feed. The right choice depends on:
- Your species – Match feed type to natural feeding behaviour
- Your system – Consider water depth, current, and infrastructure
- Your management style – Manual vs. automated feeding
- Your economics – Total cost per kg of fish, not just feed price
- Your environment – Water quality priorities and regulations
For most tilapia, catfish, and ornamental fish farmers—especially beginners—floating feed offers superior manageability and often better economics despite the higher upfront cost. For shrimp, prawns, and other bottom feeders, sinking feed is essential.
Ready to optimize your feed strategy? Contact our team for personalised recommendations based on your specific operation, or explore our guide on making your own floating fish feed to reduce costs.
