My Saddest Moment: The Sad Reality of Fish Mortality

My saddest moment was when I went to my fish farm and found hundreds of fish floating on the water surface in the pond, indicating that they were dead.

In this article, I am going to share with you the biggest mortality ever in my fish farm, how it occurred, and how we managed it. So that you can also learn from that because “when a frog in front falls into a pit, those behind take caution.”

Why Was It My Saddest Moment?

It was my saddest moment because those days were the days I had the highest fish mortality ever on my fish farm. It is not that I don’t record fish mortality in my fish farm, but it’s always been low until those days.

Before those days, from fingerling, till they were Six Months, the highest I recorded was when a net I used to prevent fish predators trapped and killed five fingerlings. The net actually trapped seven, but when I got there in the morning, two were still alive, leaving five dead.

After that, I always recorded one mortality a day, two, or three, and, in a few cases, four.

But let me indicate that my fish ponds are actually two (Tarpaulin type of fish pond), and each has the capacity of One Thousand fish. This means I stocked a little over 1000 fingerlings in each pond because of contingency. And indeed, we lost more than 100 fish in each pond before their maturity. The intention was to keep the fish for up to six months before selling them out.

We stocked them on 24th July 2023, which means they were 6 months old by 24th February 2024. By February, we had purchased our smoking machine, waiting to harvest and smoke them. Which means we intended to add value to the fish. “We plan, and Allah plans, and Allah is the best of planners.” (Qur’an)

Instead of just harvesting them during the period, we decided to keep them for about a month to get more weight and bigger sizes.

My saddest moment came when I went to the farm on the morning of 5th March 2024 to clean my Recirculating Aquaculture System (RAS) and other equipment. Just to find hundreds of fish floating on the surface of the water in the pond. Upon seeing this, my heart jumped as if I had lost someone closest to me.

Before that day, the water in that particular pond had been brownish and smelled a lot, which I personally knew needed to be changed. But I never thought it was so intensive; after all, I believed the RAS would clean it for me. So I started flushing out the waste in RAS twice daily, morning and evening.

But the biggest obstacle was that I didn’t change water due to the fact that I didn’t have enough water in my fish farm. Because I’m using a borehole and the water in the borehole gets finished quickly in a day during this hot season. The water I also stored in the poly tanks was not enough to fill the fish pond. So I kept pumping the little water I had in the borehole to the poly tanks daily, hoping to get them full before changing the water in the fish pond.

Just the day I got the two poly tanks full, I also realized the fish were weaker and struggling in the water, gasping for oxygen. It means the water was overtaken by ammonia, and when ammonia is high in a fish pond, it reduces the oxygen level in the pond. The ammonia comes from the feces of the fish as they are excreted into the water. Though the RAS removes them, it is not entirely.

I also noticed due to the high ammonia content in the pond, the submersible water pump which adds oxygen to the pond was not functioning properly. It was working alright, but how it sucks and pushes air or oxygen in the pump was not so. No matter how you turn the pump, it was just ’69’. I said 69 because, if you turn 69 in the opposite direction, it won’t give you another figure but 69 again.

So when I realized the fish were weak, then I started draining out the dirty water to now change it to fresh water. By 9:00 at night, the dirty water was left with small, so I added antibiotics into the pond and started topping up the water. I returned home when I started topping up because I knew where the level would be after emptying the two poly tanks into the pond, so I wasn’t scared of overflowing.

Unfortunately, it was too late. I only returned to the farm in the morning, and hundreds of fish were dead and floating.

That day alone, we lost over 464 fish. That was the figure I could count.

The following day, we lost more again, and then we harvested the rest of the small remaining fish into a refrigerator and started smoking them.

The lesson we learned here is that the freshness of water is paramount to fish, and every fish farmer must note this. We made a slight mistake by not changing their water in time and lost almost all the fish. So learn from my mistakes to avoid them, and that is why I began by saying “When a frog in front falls into a pit, others behind take caution.”

Fish mortality. Fish floating in pond indicating they are dead

Other Causes of Fish Mortality

2. Disease and Parasites

Fish are susceptible to various diseases and parasites, as I experienced firsthand. These ailments weaken their immune systems and can lead to mortality if left untreated. Common diseases include bacterial infections, fungal infections, and parasites like ichthyophthirius (ich).

3. Overcrowding

My experience taught me that overcrowding can be detrimental to fish health. When fish are kept in tanks or ponds with limited space, stress and competition for resources like food and oxygen increase. This can lead to the spread of diseases and hinder their growth, ultimately resulting in mortality.

4. Poor Nutrition

Inadequate or imbalanced diets, as I learned, can weaken fish health and make them more susceptible to diseases and stressors. Lack of essential nutrients compromises their immune systems, ultimately leading to mortality.

5. Handling and Transportation Stress

Improper handling during transportation or transfer between tanks can cause stress, injuries, and even death, as I witnessed. Sudden changes in temperature, pH levels, and water chemistry during transportation can also contribute to mortality.

Prevention Methods

”No matter how long a walking stick is, it has its handle”. Despite the numerous causes of fish mortality, there are ways to minimize, if not prevent it entirely. Some of these measures include;

1. Maintain Optimal Water Quality

Regularly test water parameters such as pH, ammonia, nitrites, and oxygen levels, as I realized too late. Use filtration systems and perform water changes as needed to maintain clean and oxygen-rich water.

My saddest moment came as the result of being unable to manage the water quality in my fish farm. Don’t also be a victim.

2. Implement Disease Management Practices

Quarantine new fish before introducing them to existing populations, as I now understand is crucial. Regularly inspect fish for signs of illness and treat any diseases or parasites promptly with appropriate medications.

3. Avoid Overcrowding

Provide adequate space for fish to swim and minimize stocking densities, as I learned firsthand. Monitor population levels and adjust stocking densities as needed to prevent overcrowding and reduce stress on the fish.

4. Provide Proper Nutrition

Feed fish a balanced diet that meets their nutritional requirements, which I now know is essential. Offer a variety of foods to ensure they receive essential nutrients, and avoid overfeeding to prevent water quality issues.

5. Handle Fish Carefully During Transportation

Use appropriate containers and packaging materials to minimize stress and injuries during transportation, as I witnessed the consequences of improper handling. Maintain stable water conditions and avoid sudden temperature or pH fluctuations to reduce transport-related mortality.


In conclusion, I have shared my saddest moment with you for you to learn and avoid them to be successful in your fish farm business. As evidenced by the multitude of factors contributing to fish mortality. From disease outbreaks to overcrowding, and from poor nutrition to transportation stress, each aspect demands careful consideration and proactive management.

My personal experience serves as a poignant reminder of the importance of diligence and foresight in mitigating these risks. By implementing measures such as maintaining optimal water quality, implementing disease management practices, avoiding overcrowding, providing proper nutrition, and handling fish carefully during transportation. Fish farmers can safeguard their investments and ensure the well-being of their aquatic stock. Let us learn from past mistakes and strive to cultivate a sustainable and thriving aquaculture industry, where the health and vitality of our fish populations are prioritized at every turn.

Abdul Aziz Issah
Abdul Aziz Issah

With a solid background in fish farm management, I’ve successfully established and operated a flourishing fish farm for about a year now. Over this period, I have gained invaluable experience that I am eager to share with fish farmers, whether they are beginners or seasoned experts.

This blog is dedicated to empowering fish farmers to maximize their profits through the pool of knowledge and practical insights I will be sharing. Whether you are venturing into fish farming for commercial purposes or as a hobby, you have come to the right place. I am here to guide you every step of the way.

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