ODOUR MANAGEMENT IN FISH FARM

There are several factors limiting the operation of fish farm in different parts of the country. The most common is air pollution in terms of odour that emanates from the fish farm. This is why most fish ponds are located in rural or less-populated area where the odour has less environmental effect and it is bearable in the neighborhood. A fish farmer must find effective ways to control odour in fish ponds. This is a contingent measure to ensure the continuity of the business as population grows. An urban society used to be a rural society.
A smell of rotten eggs in fish ponds is caused by a combination of carbon dioxide and hydrogen sulphide, which are the waste products of anaerobic bacteria which work in low oxygen conditions. A heavy, swampy smell is typically noticed during and after a heavy algae bloom, where new algae are growing and old algae decomposing at a rapid pace.
There are a few common causes of pond odours, and all should be taken seriously and treated if you have fish in your pond. Even in fishless waters, a bad smell is usually an early indicator of a natural imbalance which can slowly damage the eco-system. Discovering the cause and treating the smell early will prevent major issues occurring in future, and will also stop the odour from becoming too potent for yourself and your guests!

CAUSES OF FISH POND ODOUR AND REMEDIES

1. Poor Water Filtration
A pond without a means of water filtration will slowly see an increase in waste matter that can contribute to smelly pond water. Earthen ponds which don’t have a dedicated filter box need to be carefully balanced with natural filters, such as pond plants, otherwise there is no method of removing excess nutrients from the water. In a natural pond, plants and algae will make use of waste build-up (sludge) and excess water nutrients for growth, acting as natural filtration systems.
For a pond with fish, a dedicated filter system and pond pump is required to effectively process the bio-load of organic waste produced. Without a filter, or with an underperforming one, harmful substances and organic matter will slowly build to dangerous levels leading to all sorts of problems, including unpleasant smells. Ensuring your filter and pump are the correct size for your pond and keeping up with maintenance is essential for a healthy fish pond

2. Stagnant Pond Water (Low aeration)

Lack of aeration will lead to low oxygen conditions and encourage nuisance algae growth and smelly pond bacteria.
The number one cause of bad pond smells is due to a lack of water aeration, which usually results in a strong smell of rotten eggs. A pond needs to have some level of water movement or it will eventually begin to stagnate. Aeration provides a pond fresh oxygen, nutrients, and water flow, which helps prevent a build-up of substances in any one area. Pond stagnation usually produces a strong smell of rotten eggs.
The smell is caused by bacteria which slowly breakdown waste at the bottom of a pond using enzymes. Due to the low amounts of dissolved oxygen in stagnant ponds, normal aerobic bacteria cannot break down substances as they need large amounts of oxygen to function. In the absence of oxygen, slow digesting anaerobic bacteria take over and slowly reduce pond waste. The problem with this process is harmful by-products of carbon dioxide and hydrogen sulphide are released and slowly build at the bottom of a pond.

3. Pond Sludge (Bottom muck)
Sludge at the bottom of a pond is normal, but if the amount of muck gets too high, you may begin to smell a problem on the surface. Pond sludge is simply all the organic matter in a pond which sinks to the bottom and begins to decompose. All ponds will have some level of sludge, and pond plants will be able to use it as a natural fertilizer for nutrients. If you have a large number of pond fish producing waste, or your pond is surrounded by trees and plants that drop leaves, sludge levels can slowly build over time.
Sludge that is close to the water surface will begin to affect the smell of the pond and become noticeable, typically producing a smell of rotting vegetation and eggs. If you notice sludge that is thick, black in color, and slowly building up, it is very likely contributing to the bad pond odour.

4. Dead fish in the pond
Stagnant water can kill fish due to low oxygen content and harmful spikes in chemicals, such as ammonia and nitrites.
This is a common cause if you have had a particular harsh weather  with a large amount of waste present. Fish may also die  due to lack of oxygen or a build up of harmful gases under the surface.
Decaying fish will produce a high concentration of harmful substances in comparison to decaying foliage, so they need to be removed  immediately.

5. Overgrowth of Algae
Another common cause of bad pond smells is an overabundance of pond algae. The spike in decomposing algae can place enormous stress on a ponds eco-system, as well as greatly reduce oxygen content which fish need to survive. The natural pond bacteria which break down organic waste require oxygen to function, and as algae die off so rapidly, oxygen is quickly depleted. Bacteria which can’t keep up with decaying matter means harmful substances will begin to slowly build up, which can lead to potent smells and bad water odor.
Algae growth should be checked regularly to avoid overgrowth.


Professional advice;
 10-20% of the pond water should be  drained weekly or as frequent as desired to maintain a habitable ecosystem and replaced with fresh water from the tap or well. This will make oxygen steadily available and environmental friendly