Based on a research by Ahmed bin Mohammed Al-Noumani, Supervised by Dr. Wenresti Gallardo and Dr. Ahmed bin Said Al-Sooti

Department of Marine Science and Fisheries, College of Agricultural and Marine Sciences

As the demand for efficient and sustainable aquaculture practices continues to grow, even the smallest details in fish breeding systems can make a significant difference. A recent undergraduate research project is shedding light on how simple changes in tank design, specifically, the type of spawning substrate, can dramatically improve fish reproduction outcomes.

The study, conducted by student Ahmed bin Mohammed Al-Noumani, focuses on zebrafish (Danio rerio), a globally important model species widely used in biological and aquaculture research. Known for their rapid reproduction and transparent embryos, zebrafish provide an ideal system for investigating factors that influence breeding success and early life-stage survival.

In natural and controlled environments alike, the physical structure of a habitat plays a crucial role in fish reproduction. Substrates (materials placed at the bottom of tanks) can influence where fish spawn, how eggs are protected, and ultimately how many larvae survive.

To better understand this relationship, the study compared three different spawning conditions: 1) Hydrostone (a porous, structured material), 2) Glass marbles (commonly used in laboratory systems), 3) No substrate (control).  

The experiment was carried out over several weeks using carefully managed breeding conditions, with consistent monitoring of water quality, fish behaviour, and larval production.

Interestingly, the research found that key physical water parameters such as temperature and dissolved oxygen remained stable across all treatments. However, chemical parameters, including pH and nitrogen compounds, showed clear differences depending on the substrate used.

Hydrostone, in particular, demonstrated strong biological filtration properties. Its porous structure provided an ideal surface for beneficial microbial communities, helping maintain low levels of harmful nitrogen compounds such as nitrate and nitrate. This highlights the importance of microbial processes in maintaining healthy aquaculture systems.

While water quality remained largely controlled, the most striking results were seen in reproductive output.

Across three breeding cycles, Hydrostone significantly outperformed the other treatments, producing over 60% of total larvae, compared to 27.7% for glass marbles and just 11.6% for tanks without substrate.

This improvement is attributed to several key factors: 1) Enhanced egg protection: Eggs settle in between hydrostones, reducing predation by adult fish, 2) Complex microhabitats: The structure creates safe spaces for embryos and larvae, 3) Natural feeding support: Microbial biofilms may provide early nutrition for newly hatched larvae. 

In contrast, eggs in tanks without substrate remained exposed on flat surfaces, making them highly vulnerable, while glass marbles offered only partial protection.

One of the most important insights from the study is that reproductive success was not driven by water chemistry alone. Even in a shared water system with similar environmental conditions, larval production varied dramatically based on the physical structure of the substrate.

This finding underscores a critical principle in aquaculture: habitat design matters as much as water quality. The physical environment can directly influence fish behaviour, spawning efficiency, and survival rates.

Although zebrafish are primarily used as a model organism, the implications of this study extend far beyond the laboratory. Optimising spawning substrates could improve breeding efficiency in a wide range of aquaculture species, contributing to more productive and sustainable fish farming systems.

The research also aligns with broader efforts at SQU to advance innovative and practical solutions in aquaculture, similar to ongoing work in integrated systems such as aquaponics, which emphasise efficiency, sustainability, and resource optimisation.

This project highlights the strong research culture within the Department of Marine Science and Fisheries, College of Agricultural and Marine Sciences, where undergraduate students are actively contributing to scientific discovery. Through hands-on experimentation and rigorous analysis, students are helping to address real-world challenges in food production and environmental management.

As Oman continues to prioritise sustainable resource use, research like this demonstrates how targeted scientific inquiry, down to the level of substrate design, can yield impactful results.

A full scientific report detailing the findings will be submitted to a journal to provide valuable insights for aquaculture practitioners and researchers alike, reinforcing SQU’s role in advancing aquaculture techniques.