Why Do Half Of My Fish Have Bloodshot Eyes? (Answered!)

It can be frightening to look at your fish and realizing their eyes are red.

This is far more common than fish owners think and it’s important to get to the bottom of things quickly. It starts by asking, “Why do half of my fish have bloodshot eyes?”

Fish can have bloodshot eyes when there’s ammonia or chlorine present in the water. In some cases, it may involve a foreign substance entering the water like polish, deodorants, or air fresheners.

It’s important to resolve this issue by using a test kit to test the ammonia level in the water. If it’s high, the best course of action is to change the water in the fish tank.

Fish red eyes can be difficult for owners to see but it’s important to take action immediately. This article will shed light on what causes red eyes in fish and what to do about it.

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What Causes Red Eyes In Fish?

1. Ammonia or Chlorine

The most common cause of red eyes in fish is excess ammonia or chlorine.

This can change the pH level in the water making it dangerous for fish to live. Depending on how much of the tank has been affected, this can cause specific fish to respond badly to the increase in ammonia.

In situations such as this, it’s important to test for ammonia in the fish tank right away. Letting this continue for too long will lead to the fish dying.

It’s recommended to see where the fish are swimming.

If they are swimming at the bottom of the fish tank then it is likely due to an increase in ammonia.

2. Swim Bladder Disease

Swim bladder disease is a condition that can cause a wide array of symptoms in fish.

This can include red eyes, swimming on their sides, and/or general refusal to eat. With a condition such as this, it’s important to assess what’s going on and then come up with a viable treatment plan.

This begins by changing the water in the fish tank.

3. Foreign Chemical

This is not as common as the other causes but it is possible.

A foreign chemical entering the water can be dangerous for fish. This can be something as simple as pouring nail polish into the water or adding an air freshener into the tank.

It might happen by mistake but it can do a lot of damage if the water isn’t changed immediately.

Tips For Helping Fish With Bloodshot Eyes

1. Use a Test Kit To Check For Ammonia or Chlorine

If a fish has red eyes, it’s best to look at the pH level in the fish tank.

This will let you know whether or not ammonia and/or chlorine are the root cause. If there is too much ammonia in the water, it can become dangerous for the fish to swim in the tank.

You will have to remove them from the fish tank, run the test, and see what the level is.

It will let you know what needs to happen next.

why do half of my fish have bloodshot eyes

2. Change the Water Immediately

You will want to change the water regardless of what the root cause is.

With red eyes fish in the tank, it’s important to realize the water chemistry is off. This is something you can’t deny whether it has to do with parasites, bacteria, and/or a foreign chemical.

Whatever the reason may be, you have to change the water in the fish tank as soon as possible.

Changing the water in the fish tank will help refresh or reset the pH level in the tank and make it easier for the fish to stay healthy.

This should be happening regularly.

You don’t want a situation where the water worsens and starts killing all of the fish in the tank. If it is only a few fish right now, this means the problem just started and it has not spiraled out of control.

You can still reel things in a bit.

why do half of my fish have bloodshot eyes

3. Check for Secondary Symptoms

You should always check for secondary symptoms when it comes to red eyes in fish.

The goal is to see how the fish is swimming.

If the fish is swimming at the bottom of the tank then it is likely dealing with a bacterial issue. This includes too much ammonia in the water causing it to become a dangerous place for the fish to swim in.

Fish with red eyes swimming on their sides may be dealing with swim bladder disease as this can also lead to red eyes in fish.

Continue to look at the fish to see how they are doing.

The signs will become apparent one way or the other.

Related Questions

1. Why Does My Fish Have A Bloodshot Eye?

A fish can have a bloodshot eye due to an increase in ammonia or chlorine in the water. It is also possible for parasites or foreign chemicals to be the reason for the bloodshot eyes. It’s best to run a test kit in the water to see what the issue is.

2. Can A Fish Eye Heal?

A fish eye can heal at the cellular level. This regeneration process can be slow but it is possible in fish, unlike humans.

Final Thoughts

Why do half of my fish have bloodshot eyes?

Your fish may have bloodshot eyes because there’s too much ammonia, chlorine, or foreign chemical in the water. This can cause the water chemistry to change leading to a wide array of symptoms in fish including bloodshot eyes and erratic swimming patterns.

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