Could a special mix of microbes in fish water, known as biofloc, be the key to growing more fish and plants together? A recent paper from South Korea, titled “Indoor application of a coupled FLOCponics system with caipira lettuce (Lactuca sativa) affects the growth performance and water characteristics for Far Eastern catfish (Silurus asotus) and tropical eel (Anguilla bicolor)” and made available as a preprint in May 2025, explores this very idea. Researchers investigated if combining biofloc technology (BFT) with aquaponics, a system they call “FLOCponics,” could improve how we farm these high-value species.
The study compared traditional flow-through systems with BFT alone and the FLOCponics setup for growing Far Eastern catfish and tropical eels, alongside caipira lettuce. The good news? Both catfish and eels grew better in the FLOCponics and BFT systems than in the standard flow-through tanks. This suggests the biofloc, which is a mix of tiny living things like bacteria, might be helping the fish thrive, perhaps by providing extra food or keeping the water cleaner. For the plants, lettuce grown with water from the catfish tanks did just as well as lettuce grown in a typical hydroponics system. This is a big plus, showing fish water can indeed be rich enough for healthy crops.
However, it wasn’t all smooth sailing. When lettuce was paired with the tropical eels in the FLOCponics system, the plant roots started to degrade, leading to smaller lettuce. The researchers think this might be due to too many solids from the eel system or perhaps changes in water chemistry, like higher sodium from pH adjustments, affecting the delicate roots. Water quality, in terms of harmful ammonia and nitrite, remained stable across the tests, which is important for fish health. Nitrate, a plant nutrient, was used up by the lettuce in the FLOCponics system, which is exactly what we want to see.
This research hints at the potential of FLOCponics to make aquaculture more efficient. Yet, the eel-lettuce problem highlights a critical point: what works for one fish species might not work for another, or for all plants. It’s a reminder that while new methods are exciting, they often need careful tweaking. As this is a preprint study, it hasn’t yet undergone the full scrutiny of peer review by other scientists.
Still, it provides useful food for thought on how we can better integrate fish and plant farming, though we’ll need more research to iron out the kinks, especially for sensitive species combinations.