ISBN 0532-940X

Water quality and fish health


Zdenka Svobodová
Research Institute of Fish Culture and Hydrobiology
Vodnany, Czech Republic

Richard Lloyd
“Wild Oaks”, Woodside
Little Baddow, Chelmsford
Essex, United Kingdom

Jana Máchová
Blanka Vykusová
Research Institute of Fish Culture and Hydrobiology
Vodnany, Czech Republic

The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.

ISBN 92-5-103437-0

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying or otherwise, without the prior permission of the copyright owner. Applications for such permission, with a statement of the purpose and extent of the reproduction, should be addressed to the Director, Publications Division, Food and Agriculture Organization of the United Nations, Viale delle Terme di Caracalla, 00100 Rome, Italy.

Svobodová, Z.; Lloyd, R.; Máchová, J.; Vykusová, B.
Water quality and fish health.
EIFAC Technical Paper. No. 54. Rome, FAO. 1993. 59 p.
This publication is in a nature of a textbook. After the introduction on the natural and man-made inputs causing elevated levels of chemicals and organic matter in water, the text reviews the general responses of fish to such situations. A major chapter looks into the causes and effects of pollution on fish: harmful variations in natural water quality characteristics and chemicals in water as a result of man's activities. This is followed by a discussion on diagnosis of causes of fish poisoning, with a detailed checklist as an example of the information necessary to document a local investigation into the cause of abrupt changes in the behaviour or of mortality of fish. The chapter on the control of water quality includes general principles for preventing fish poisoning, evaluation of chemicals, preparations and effluents, persistence of substances in aquatic environment, and legislation. The final chapter briefly discusses pollution in relation to viral, bacterial and fungal diseases, and fish parasites.


This publication is the result of edited lectures presented at the FAO (GCP/INT/526/JPN) International Training Course on Freshwater Fish Diseases and Intoxications: Diagnosis, Prophylaxis and Therapy, held in Vodnany, Czechoslovakia, June 15 – July 3, 1992. It is intended to serve as a training tool for similar courses, but it can be used also in courses of a broader character, as well as by fisheries managers seeking general background information in this field.

Comments and suggestions for additions and modifications of the text may be addressed to the authors of this publication. Copies of this document can be obtained from The Secretary, EIFAC, FAO, Fisheries Department, 00100 Rome, Italy, or from FAO, Distribution and Sales, at the same address.


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© FAO 1993

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1.   Introduction

2.   A brief review of adaptive mechanisms in fish

2.1   Respiration

2.2   Osmoregulation

2.3   Toxic substances in the water

2.4   Conclusions

3.   Causes and effects of pollution on fish

3.1   Harmful variations in natural water quality characteristics

3.1.1     Water temperature

3.1.2     Water pH

3.1.3     Dissolved oxygen

3.1.4     Supersaturation with dissolved gas

3.1.5     Ammonia     Factors associated with ammonia toxicity     A field study of toxic gill necrosis in carp, and preventative measures

3.1.6     Nitrites and nitrates

3.1.7     Hydrogen sulphide (H2S)

3.1.8     Carbon dioxide

3.1.9     Summary

3.2   Chemicals in water as a result of man's activities

3.2.1     Chlorine

3.2.2     Cyanides

3.2.3     Divalent metals and their salts     Aluminium     Chromium     Iron     Nickel     Copper     Zinc     Arsenic     Cadmium     Mercury   Lead

3.2.4     Phenols

3.2.5     Polychlorinated biphenyls (PCBs)

3.2.6     Surfactants

3.2.7     Pesticides     Chlorohydrocarbon (i.e. organochlorine) pesticides     Organo-phosphorus pesticides     Carbamate and thiocarbamate pesticides     Pesticides based on carboxylic acid derivatives     Pesticides based on substituted urea     Diazine and triazine pesticides     Synthetic pyrethroid pesticides     Pesticides based on metal compounds

3.2.8     Oils and refined products

3.2.9     Dyes

3.2.10   Phytoplankton toxins

4.   Diagnosing the cause of fish poisoning

4.1   Examination in situ

4.2   Hydrochemical examination

4.2.1     Water samples

4.2.2     Sediment samples

4.3   Hydrobiological examination

4.3.1     Aquatic communities

4.3.2     Examination of periphyton

4.3.3     Biological assay for water toxicity testing

4.3.4     Examination of the fish

5.   Control of water quality

5.1   General principles for preventing fish poisoning

5.2   Evaluation of the chemicals, preparations and effluents

5.2.1     General principles

5.2.2     Acute toxicity tests

5.2.3     Chronic toxicity tests

5.2.4     Other toxicity tests

5.3   Persistence of substances in aquatic environment

5.4   Legislation

6.   Pollution and fish diseases

6.1   Viral diseases

6.2   Bacterial diseases

6.3   Fungal diseases

6.4   Fish parasites

6.5   Conclusion


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