Previous Page Table of Contents Next Page


The following table, which provides a summary of the toxic and anti-metabolite elements occurring in common feedstuffs which are known to affect aquaculture species, is extracted from New, (1986a):

Toxin or Antimetabolite


Factor or Effect

Examples of sources

Fungal toxins



Produced by the mould Aspergillus spp., which grows, particularly in high temperature/high humidity conditions, on ingredients and compund feeds, particularly groundnut meals and cereals

T-2 toxins

As above, orginating from the mould, Fusarium spp.


Caused by Fusarium spp.

General deterioration of feed quality

Caused by Penicillium spp. moulds

Bacterial infection


Salmonella contamination

Contaminated ingredients, especially animal proteins, together with insects and rodent droppings


Unpasteurized trash fish and viscera

Bacterial toxins


Trash fish stored anaerobically

Chemical contaminants

Pesticides and Herbicides, such as organo chlorine and poly chlorinated biphenyls (PCB's).

Plant ingredients, contaminated by spraying, and accumulation in fish and fish products used as ingredients

Heavy metals,e.g., Mercury

Concentrated by animals and plants used as ingredient sources


Contamination of feeds by traces of chemicals used during feed processing e.g., lubricants, fumigants, water softening chemicals, etc.

Volatile N-nitrosamines (VNA)

Fish meal, especially that dried by hot air exhausted from an oil burner (direct heating/drying method)

Natural feed components


Cyclopropenoid acids Synergistic effect on aflatoxins and act as growth inhibitors.

Kapok and cottonseed oils

Cyanogenetic glycosides


In expeller linseed meals, lima beans, cassava


From damaged or old sorghum and maize

Vitamin antagonists

Linatine (Anti-vitamin B6)

Expeller linseed meals

Lipoxidase (Anti-vitamin A)

Soybean meal

Antivitamin D

Soybean meal

Antivitamin B1. (Thiaminase)

An enzyme present in raw fish, particularly freshwater fish, herrings, mussels, clams, and shrimp

Antivitamin E

From kidney and haricot beans. (Note: vitamin E deficiency also caused by lipid rancidity)

Antibiotins (e.g., Avidin)

In raw egg white; normally egg (used in larval diets) is cooked. Biotin can also be inactivated by rancid fats


Green parts of potato plants


Growth inhibitor from ipil-ipil (tangen-tangen)

Toxic amino acids

Chick peas

Natural feed components (continued)


Gossypol (reduces amino acid availability)

Pigment from cottonseed products


Rapeseed and mustard seed meals

Oxalic acid

Sugar beet

Phytates (from complexes with proteins, phosphorus, calcium, zinc, copper, magnesium, etc., thus reducing availability of these components)

Soybean, sesame, groundnut and cottonseed meals; cereal hulls, germ and endosperm

Protease inhibitors (affects activity of the trypsins and exacerbates sulphur-amino acid deficiencies)

Unheated or underheated soybean meal and protein concentrates


Unheated soybean meal; various species of beans

Sapogenin glycosides

Soybean meal, alfalfa, sugar beet (not normally toxic but water extracts of some extracted saponins are used to kill fish during harvesting in some locations)


Oxidised oils

Poorly stored and inadequately protected (by antioxidants) ingredients, particularly those with high poly-unsaturated fatty acid levels such as fish oils and meals.

Previous Page Top of Page Next Page