Most times, the greatest challenge a fish farmer can face in a fish farm is how to effectively regulate the Fish pond water quality. On the other hand, most farmers do not know the parameters for pond water testing while the rest have no idea of what a pond water management is.
In any case, ignorance is never an excuse and there are no two ways about having healthy fishes with poor water management. In other words, if you allow the fish pond water to get toxic to the fishes, they will have no other option than to get sick or to die.
However, the water quality is dynamic and can change at anytime because Fishes eat, live and deposit waste products in water. Also, the external environmental factors can heavily affect the pond water quality parameters.
Therefore, there is need for constant monitoring and analysis of the water to know which parameter needs to be addressed.
In this post, we will discuss those parameters, their ranges and proactive measures to keep the water safe for fishes.
Pond water quality parameters to monitor
Quality water for fish pond should meet a standard necessary for survival of fishes. Meanwhile, there are 6 water parameters to test to ensure that the fish water is still safe. As a matter of fact, i advice every farmer to have a complete fish water test kits to always detect any irregularity early and handle it.
The 6 water parameters to monitor in a fish pond includes;
- Dissolved Oxygen
- Pollutants and Fish wastes such as Ammonia, Nitrogenous waste and Carbon dioxide.
- Microbial load
Dissolved Oxygen (DO)
Fish require adequate concentrations of dissolved oxygen for survival and growth. There are three ways oxygen can be produced in the fish pond.
- Oxygen dissolves in water from the atmosphere.
- From Aquatic plant’s photosynthesis.
- Through mechanical aeration.
However, when there is threat of oxygen depletion in the pond, the best source is to either change the water completely or provide a mechanical aerator.
Oxygen of 4 mg/ Litre and above is considered adequate for fish. As a result, lower oxygen levels can result to the fishes not feeding well or vomiting their feeds. This can hinder growth and also serve as a waste of feed.
Shortage of oxygen most times is as a result of competition for oxygen in the case of over stocking. In addition, decay of organic materials or decomposition of uneaten feed in the water can also deplete oxygen concentration.
Basically, If oxygen is in short supply, fishes become restless, swimming to the surface to gasp for air. In very acute oxygen shortage, the fish will be jumping out of water. Again, foul smell of water is another indicator of low oxygen.
Dissolved oxygen is measured using the DO metre or DO testing equipment. This device measures oxygen concentration in both milligrams per litre (mg/)l and percentage saturation (% sat) – just like oximeters used in the hospital.
Conversely, in a traditional setting where the farmer has no DO meter, the condition of Dissolved oxygen in the water can be tested by spitting into the water. If the foam remains intact over 5-6 minutes, oxygen is low in the water. Other factors to look out for is the smell of the water, the reaction of the fishes such as jumping out of water or vomiting after feeding.
This is a measure of acidity or alkalinity level of water. The pH scale ranges from 0 -14. The neutral pH point is 7, the pH above 7 is alkaline while below is acidic.
The best water for fish culture is neutral or slightly alkaline (pH 6.5 – 8.5). Notably, pH less or greater than that range is toxic to fishes and can induce stress or death.
Notwithstanding, the major cause of fluctuation in pH is the presence of Carbon dioxide, dissolved minerals and ammonia. Fish Pond Liming and treatment is necessary to correct acidic pH while addition of Sodium bicarbonate to pond water under expert supervision can correct extreme alkaline condition.
You can determine the pH of your pond H20 by the use of pH indicator paper. The paper indicator changes color when dip in pond water and the color is matched with the color indicated on the chart to determine the pH level of the water. On the other hand, the farm can choose to use an electronic pH meter. However, the cost of using the paper strips is cheaper than the pH metre.
pH Table and level of risk
pH < 4 Acidic death point
4.0 – 5.0 No reproduction
4.0 – 6.5 Slow growth
6.5 – 8.5 Desirable range
9.0 – 11.0 Slow growth
pH > 11 Alkaline death point
Suspended particles, silt and clay in ponds usually make water look cloudy. As a result, turbidity reduces light penetration and level of photosynthesis. This in turn can cause low food production by plants and inadequate aeration of the pond.
You can tell if your pond water is turbid if you notice a change of color from slightly Greenish to Brown. Also if you dip your hand inside pond water and discovered that your palm cannot be seen before your elbow reaches the water level, then the water is turbid.
Another method of measuring pond water turbidity is the use of the Secchi disc. Secchi disc
reading (visibility) of 40- 90 cm is adequate for a standard pond water quality.
If turbidity is as a result of run-off around the pond, drainage can be constructed to divert it away. On the contrary, the water can be changed completely or Alum at 1.3 kg over 100 m2 can be added to the water under expert supervision.
Pollutants and Fish wastes
Wastes are from uneaten food, CO2 given out during respiration and fish feaces. Accumulation of wastes can be noticed though foul smelling emanating from the water or color changes in water. Therefore, the farmer is to be observant to notice these changes in the pond water quality.
As a preventive measure, do not over feed fish or remove uneaten feed before it becomes nuisance. Also, You can drain the water off completely and replace with fresh one as a last resort.
Other fish water pollutants includes; waste materials from agricultural industries and households, which find their way into the pond water. Oil film scum foam and sometimes massive death of fish
could indicated presence of pollutants in water.
Temperature of the pond water plays an important role since it affects the rate of dissolution of oxygen. In other words, cold water retains more oxygen than warm water. The optimal range for pond water temperature in aquaculture is 24 to 34 0C and 26 to 28 0C for rearing of fry and egg development.
Fluctuations in temperature can induce stress and change to physiological characteristics of the fishes. Therefore, the fish farmer is to check the temperature of the pond at intervals with a thermometer.
Abnormally high temperature can be controlled by mixing the water with colder water or by covering part of the pond from direct sunlight. On the other hand, lower temperatures can be controlled by installing a regulated heater especially after rainfall or cold nights.
Microorganisms are the major cause of many fish diseases and can as well contaminate the pond. Bacteria and fungi are the chief source of pond water quality contamination. Hence, when a farmer notice any form of physiological change in the fishes, it is wise to take a sample of the pond water for microbial analysis and profiling.
Alternatively, the farmer can drain the pond and apply table salt, Copper sulphate or Formalin for some minutes. However, mistake with knowing the quantity to decontaminate the pond and duration can cause fatality to the fishes. Traditionally, we use bitter leaf (Vernonia amygdalina) water to decontaminate the pond, it is safer.
Optimal Pond water quality requirement for Catfish
Temperature 27 – 30 o C
pH 6.5 – 8. 5
Dissolved Oxygen >3. 0 mg /litre
Carbon dioxide < 20 mg /litre
Total alkalinity 50 – 100 mg /litre (CaCO3)
Un-ionized ammonia < 0. 1 mg /litre
Nitrite 0.5 mg / litre
Proactive measures to maintain an optimal pond water quality
The proactive measures are what you need to put in place to help maintain the optimal conditions for pond water quality. Meaning, you will not have to wait till your water get contaminated before you seek for solution – you may not be that lucky.
Therefore, here are few stuffs that will help to induce a good water profile for your fish pond.
- Protect the pond from direct sun or rain: Do not expose the pond to these two factors as they can affect the temperature and also the DO of the water.
- Use pond filters: both mechanical and biological pond filters keeps the pond clean and safe by removing debris and bacteria from the pond water.
- Do not over feed the fishes: Overfeeding is a waste of feed and source of contamination of the pond water quality. Leftover foods can decompose and release NH3, CO2 and H2S which are toxic to fishes. Therefore, Learn the proper way to feed fishes
- Introduce aqua plants: Aqua plants take nitrogenous wastes and CO2 from water and give out oxygen as a byproduct. As a result helps to balance the O2 and CO2 cycle.
- Remove any dead organic matter: Make sure you remove dead organic matters such as leaves that fell inside the pond.
- Avoid overstocking: Overstocking can lead to excess production of waste and easy depletion of dissolved oxygen. The recommended stocking density for earthen pond is 20-30 fish/m2, while in concrete tank with adequate water, 40-50 fish/m2.
- Choose a good location for pond: During Fish Pond construction; locate pond water sources away from pollution from industries, homes etc.
Fish pond water quality monitoring, profiling and management is the cornerstone of How to succeed in Fish farming business. Therefore, make sure that you detect fluctuations early and take care of it.
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