There are many different mud crab boxes that are available in the market right now.
While they all seem to look the same, they differ in aspects that might impact profitability.
In this article, we will focus on the 5 important considerations for box selection. While it is important to understand the specification needed, it is also important to understand the requirements of the business model.
The first consideration for selecting the box needed for mud crab aquaculture is the actual size of the box. The size of the box determines the maximum size of crab that can be farmed in the vertical mud crab boxes. It is ideal for crabs to be held in bigger spaces much like the environment they originate from. Confining mud crabs in small areas results in lower feeding rates, slower growths and longer intermolt periods. Nevertheless utilizing bigger boxes will often require a larger floor area, that results in higher rental costs for farm operators. While some have attempted to stack the boxes higher to reduce the floor area requirement, they often have lower productivity due to the need to work at heights. Therefore, it is crucial to understand the actual production method (soft-shell, grow-out, or fattening) you are planning for and measuring trade-offs between size, rental and labor cost.
Durability is also important to consider when choosing a box for your vertical farm. Certain species can be quite destructive during confinement, damaging your equipment (mainly the boxes, lids, and piping). Boxes that are damaged would require maintenance or replacement in certain extreme cases. This adds on to the additional maintenance cost required to service the boxes. Apart from the damage caused by the crabs, we would need to expect additional wear and tear from handling. Lids of the boxes need to be opened at least 2-3 times per day for feeding, monitoring, and cleaning. Boxes and piping are occasionally disassembled for disinfection to ensure low bacterial count in the system. While plastic boxes typically have a lifespan of 8-10 years, it is important to factor in the additional wear and tears into the lifespan. Most importantly, it is to make sure your boxes have a lifespan exceeds the time needed to recoup your investment.
Mud crabs will consume feed and produce fecal matters. Leftover feed and waste need to be quickly removed from the culture water to avoid contamination. Typical boxes using the stand-off piping system usually requires human intervention to clean the box individually. This amounts to a high operating cost especially locations with expensive labor. New boxes design has also incorporated a flush valve in the boxes to ensure that waste is removed more efficiently. However, this extra function would often result in a higher manufacturing cost. It is also important to mention 20-30% of the labor cost can be associated to maintain the cleanliness of the box. Farm operators should evaluate the benefits of a higher productivity system as suppose to a lower-cost product.
Apart from removing waste, boxes have to be designed for maximum productivity. Fundamentally, keeping the crabs in individual containers prevents cannibalism but also complicates feeding, monitoring, and harvesting. Crab needs to be fed individually for the vertical farm as compared to the communal feeding methods for traditional ponds. Box selection criteria should be also based on how easily can feeding, monitoring and harvesting can be done. Some boxes also have see-through lids or transparent covers that removes the need for opening and closing the lids while feeding. Stronger crabs can also temper with stand-off pipes in the boxes, resulting in loss of water and requiring human intervention. Simple design changes in the box can have substantial savings due to productivity improvement.
Mud crabs are essentially a nocturnal species, and they are most active during the night. In traditional mud ponds, it is estimated that up to 20% is lost due to mud crabs that have escaped during the night. This problem also plagues the mud crab vertical farm, where some crabs can escape from their enclosure. Common escape points for the boxes include piping connections and other small openings. It is also common for some crabs that pry open the box lids and escaping the box itself. Crabs that managed to escape from their enclosure often will end up dying due to the fall, cracking their shell while bleeding to death. While others that escape to the adjacent boxes are cannibalized by their neighbors.
Finding the best box is no easy feat, given the different products and features that each box supplier provides. Hopefully, this guide is useful for those who are about to pick their ideal boxes for mud crab farming.