In aquaculture, innovation often begins with small but significant changes, such as advancements in the use of microalgae. For decades, live phytoplankton has been the foundation of natural food production in Philippine milkfish hatcheries. Recently, however, algal paste has emerged as a promising alternative.

Algal paste is a concentrated form of microalgae (such as Nannochloropsis) that has been harvested, preserved under refrigeration, and packaged in a paste-like form. It offers several practical advantages: a longer shelf life, ease of storage and handling, and reduced need for continuous culture maintenance. These benefits translate into lower labor requirements, reduced operational costs, and more efficient use of space. Furthermore, algal paste provides a reliable backup when live phytoplankton cultures fail, a common issue in hatchery operations, while maintaining consistent quality and nutritional value.

Despite these advantages, the commercial use of algal paste in the Philippines remains limited. To address this gap, the DA-National Fisheries Research and Development Institute (NFRDI) conducted a study to assess its viability as a sustainable and efficient alternative to conventional live phytoplankton.

Technology validation trials

The validation study was implemented in two phases to compare algal paste and live Nannochloropsis cultures. The first phase was conducted under controlled conditions at the NFRDI research facility in Taal, Batangas, while the second phase took place at Bureau of Fisheries and Aquatic Resources (BFAR) legislated hatcheries in Perez and Tagkawayan, Quezon, simulating real hatchery environments.

The study covered three key stages of hatchery operation: 1) rotifer mass culture, 2) phytoplankton mass culture, and 3) milkfish (Chanos chanos) larval rearing. Two treatments were tested: T1: Algal paste – a shelf-stable, ready-to-use product, and T2: Conventional phytoplankton – live cultures maintained and harvested regularly.

The trials aimed to evaluate the performance, practicality, and potential economic feasibility of algal paste as a replacement or supplement to live phytoplankton.

Results and observations

The findings demonstrated that rotifers, which serve as essential live food for milkfish larvae, exhibited similar growth rates when fed with algal paste or live phytoplankton. This indicates that algal paste can sustain rotifer production effectively under both laboratory and operational hatchery conditions.

Moreover, algal paste was successfully used as a starter culture for growing live phytoplankton, performing comparably to traditional live cultures in terms of rotifer productivity.

In terms of milkfish fry survival, both treatments produced high and comparable results. While live phytoplankton yielded slightly higher survival rates in controlled NFRDI trials, the difference was negligible under real hatchery conditions. These results suggest that algal paste is a practical and effective option for milkfish hatcheries.

Challenges to wider adoption

Despite its technical potential, the widespread adoption of algal paste faces economic barriers. The product’s current market price remains relatively high, limiting its accessibility for small- and medium-scale hatchery operators. Until local production scales up and cost-effective formulations become available, the use of algal paste is likely to remain supplementary rather than standard practice.

Balanced approach

The study suggests a hybrid strategy for hatchery operators: using algal paste during critical phases of operation, such as initial culture establishment or in cases of live algae culture failure, while maintaining conventional live phytoplankton for regular feeding. This combined approach provides both flexibility and operational security, ensuring stable production without incurring excessive costs.

Toward sustainable hatchery practices

The integration of algal paste into hatchery management represents more than just a technological upgrade; it supports the broader goals of sustainability and resilience in aquaculture. As the Philippines continues to strengthen its role in global milkfish production, innovations such as algal paste offer a pathway toward more efficient, resource-conscious hatchery operations.

With ongoing research and institutional support from NFRDI and BFAR, the future of aquaculture feed innovation in the country looks increasingly promising—small advances in microalgae technology leading to significant impacts on food security and marine resource management. ### (Frederick Muyot)