Image credit: IntraFish


Aquaculture which entails the farming of fish, crustaceans, molluscs, aquatic plants, algae and other organisms usually in a controlled system, is still one of the fastest growing food production sectors globally. However, there have been increasing reports of chemical and other abusive use of substances in aquaculture farms, as well as food contamination in investigated aquatic edible food, including those sold in public market places, especially in Africa and Asia.


This occurrence has the potential of undermining the productivity of a sector which has, a). directly employed over 8 million fishermen and another 18 million who are engaged in fish processing, distribution and marketing, b). contributed to the socioeconomic advancement of many dependent nations and global food supply.


Many have blamed the proliferation of chemicals in aquaculture, and subsequent contamination of food, especially those sold in public market places, on weak institutions charged with the responsibility of regulating and/or monitoring the food sector.


Some of these substances which have been detected and reported both in aquaculture ponds and edible aquatic food include those classified under contaminants of emerging concern: carcinogens (its ability to cause cancer), mutagens (to cause genetic mutation), as well as those completely banned from use, for their effect on biological organisms.


Farmers introduce them to farms however, not to deliberately compromise the quality of these aquaculture products, but to maximize profit by increasing their production (farm inputs) on available land space to meet the ever growing demand for fish by a surging population. This consequently leads to a reduction in the fish quality, increase in pond disease incidence, and fish death in most cases. 


In order to stay in the business and produce the same quality, farmers abuse antibiotics and other chemical products for pond management. These chemicals which have been reported to have serious ecological and human health effects are introduced into ponds in the form of chemical fertilizers, feeds, antibiotics, antifungal agents and agrochemicals, including direct waste discharge from industrial processes, for coastal aquaculture. Sadly, fish treatment has remained one of the greatest problems in fish production systems, especially in their handling.


The danger looming in their consumption can be inferred from the 2018 FAO statistics which indicates that, fish consumption far surpassed that of meat in 2015 with fish accounting for about 17 percent animal protein consumed by the global population, estimated at 20 percent per capita intake for about 3.2 billion people . Surprisingly, over 50% of the total animal proteins consumed of fin and shell fishes alone were from developing countries and Africa in particular. A fish contribution which comes mostly from artisanal and small scale farmers has helped to combat protein deficiencies and its associated consequences especially on children in that part of the world.


The food sector whose global fish production peaked to about 17 million tonnes in 2016, with aquaculture alone representing 47% of the total and 53% of non-food use, excluding fish meal and fish oil, is increasingly compromised by detectable chemical substances reported to have both short and long term effect on body organs from consumption, and therefore underscores the need for effective monitoring of food sources to public markets.


The above statistics have provided a basis to worry over the human population who may have consumed substances detrimental to their health by eating contaminated fish and other aquatic food. For instance, a study done by Omorogie et al (2018) reported the use of sodium bisulfite, a known bleaching agent, in fish farming to slow down decomposition and abate melanosis (a condition that makes farmed shrimps to blacken). Another harmful substance is Sodium tripolyphosphate (STP), a dehydrating agent commonly used to give firmness to farmed shrimps in aquaculture ponds in Ekpan Creek, Edo State, Nigeria. Similarly, Islam et al (2014) documented an array of abused antibiotics and other chemicals used for treatment in aquaculture farms in Bangladesh.


Some farmers have attributed the observed increases in chemical use for pond management to climate change, which has precipitated temperature increase reported to influence every other physicochemical assessment of water and has altered previously known physicochemical assessments for water qualities in ponds. Farmers’ claim that climate change is responsible for the increases in their farm disease incidence however is one that is not well established.


Nevertheless, studies have documented extensively that the increasing use of chemical substances and abuse of antibiotics and other growth promoters in aquaculture effectively increases the human health risk indices of aquaculture food consumption.


This has further generated additional concern for the development of Genetic Modified Organisms (GMO’s) and food in the future, especially for coastal aquaculture designed to directly exchange water between the open river and ponds. Invariably, any pollutant present in the river water that is taken up by fish and up in the food chain to man, has serious public health implications.


It is therefore of urgent importance for governments, especially in Africa to effectively regulate and/or monitor aquaculture activities. This is necessary to safeguard public health particularly for those living in the Nigerian Niger Delta, which is associated with oil and gas activities but have aquaculture ponds dominating the length and breadth of their waters. Additionally, countries like Vietnam, which is a tourist destination in Asia and one of the top producers as well as consumers of seafood products, is reputed for open sea and coastal aquaculture farming.


Sources of some of these chemicals and/or substances

Major sources of some of these substances which raise health concern in aquaculture farms include (i) Fish feed and fertilizers (ii) Antibiotics and other veterinary drugs in use (iii) Antimicrobial agents and treatments (iv) Agro chemical and industrial pollutants.



Some of the documented human effects from the consumption of these substances include reduced intelligence quotient in children; liver, kidney, gonad damages and carcinogenicity (its ability to trigger or cause cancer). Their toxicological effects are extensive and well documented for fish life including shrimps, crabs and periwinkle, which are delicacies in most parts of the world.



From the foregoing, there is need for government and their regulatory organs, especially in Africa to urgently monitor food sources, production and chemical use. The following have been suggested for government to do:

  1. Strengthen the environmental and food policies in line with best aquaculture practice (as has successfully been done in Norway), as well as the regulatory agencies, to effectively monitor environmental pollution, in relations to effluent discharges and chemicals.
  2. The food department and/or agency must do the needful to monitor aquatic products, especially fish sold in market places.
  3. Empower its regulatory agencies with the necessary laws, manpower and trainings to effectively monitor aquaculture farms, and better understand farmers operations and practices.
  4. Farmers’ education is key not only to increase their capacity, but also to  develop the sector, discourage chemicals use and raise consumers and/or public awareness.
  5. The Environmental Ministry and counterpart agencies should monitor chemical importation and the circulation of such chemicals, especially substances that have been banned but are still in use.
  6. African governments should promote aquaculture food and products certification.


The following are suggested for farmers to do to curb the epidemic:

  1. There is need for them to engage the services of trained professionals in farm management.
  2. These farmers can form unions purposely for training needs, information and/or knowledge sharing.
  3. It is imperative for these farmers to adopt best aquaculture practices, and localize it to their environment. For example, aquaculture farms should be situated in locations away from previously polluted or pollution sites, there should be adequate control of livestock and the dumping of untreated animal manure and human waste into ponds. Proper treatment and disposal of domestic sewage, avoidance of the feeding of fish intended for human consumption with hormones beyond the hatchery stage, strict compliance with all government regulation for drug use and land, to adoption of aquaculture products certification are also best practices that need to be adopted and localized.
  4. With the growing effect of global climate change on the environment, there is also the need to patronize improved seeds and/or modified seedlings to adapt to some of these changes.
  5. Farmers should work more closely with government, especially the regulatory agencies to safeguard the aquaculture sector from collapse.


In conclusion, there is an urgent need to establish and/or improve stakeholders’ collective responsibility (including consumers), to develop and protect the aquaculture fish sector from collapse, and especially to create a synergy between the farmers and government.


The views expressed in this article are those of the author alone and not the Future Africa Forum.