Ornamental Fish Production and Management

5.1.2 pH

The pH of water usable for ornamental fish farming may vary from acidic to alkaline depending upon its source, chemical and biological factors. Marshy and peaty water has acidic pH. Similarly, water springing from a soil poor in calcium will have acidic pH.. Some ornamental fishes such as oscar and discus will spawn only in slightly acidic pH and soft water. To this, various makes of water softeners are used and inorganic acids, for example, hydrochloric acid can be used. If the pH of the water falls below the desired value, it must be increased by the addition of required doses of calcium hydroxide (slaked lime). The optimal pH for the growth and breeding of majority of the ornamental fishes should be neutral or slightly alkaline i.e. 7-8. Water in ornamental fish tanks should never fall below 5 or rise above 8.5. Ornamental fishes preferring slightly acidic pH (6.2-7) include rosy barb, tiger barb, tetra, angel and danio. On the other hand, certain fishes like cichlids, goldfish, koi and gourami prefer alkaline pH.