Sometimes aquarium plants can be dangerous for your pet fish. If you are thinking about why your aquarium’s fish are dying, inspect the plants inside the tank as they also can be responsible for killing fish. 

Can Aquarium Plants Kill Fish? Yes, aquarium plants can kill fish because of poor care and treatment. These aquarium plants can be deadly for your fish by carrying fungus, algae, pests, and other contaminants. Plastic aquarium plants can also kill your pet fish.

Plants are the vital components of an aquarium, not in terms of aesthetics but also provide several benefits to the tank’s inhabitants. They prevent algae growth by consuming the nutrients using fish wastes, leftover food, and organic debris.

Can Aquarium Plants Kill Fish?

Plant addition is the best way to enhance and uplift fish health and well-being. They act as a natural filter as well as the natural habitat for your tank.

Also, they help improve fish health and water quality by providing oxygen and eliminating carbon dioxide from the tank. Moreover, they provide fish a place to hide, play, and lay eggs.

Along with numerous benefits, plants can also be dangerous and harmful to the fish’s health and can even kill them.

Keep in mind that the health of tank inhabitants is at stake if you fail to make your aquarium plants safe. You have to take precautions before adding plants into the tank, as little carelessness can cause permanent loss. 

You can not add plants from random places into the tank as it can be extremely poisonous to the fish. Look for the plants that can live in the aquarium’s environment and conditions and add them to the tank after treating and curing. 

How aquarium plants kill fish?

Aquarium plants can become toxic and deadly to the fish by carrying harmful microorganisms, diseases, parasites, and unprofessional care and maintenance. 

Overgrowth of aquarium plants

Plants rapidly grow when you meet all their requirement and provide the essential nutrients. Also, aquarists like to add a fast-growing, easy plant in their tank, so they do not have to put effort or time into their growth. It is not always beneficial as overgrowth can kill your fish, so it is better to plant carpet seeds in an aquarium.

When plants grow out of control, they fill up the tank and cause suffocation in the tank. The fish can not breathe properly in this condition, leading to their death. All the fish, plants, invertebrates, and beneficial bacteria need oxygen and compete for it when it is not sufficient.

Although plants produce oxygen but not consistently throughout the day and need rest at some points and in the resting period, they still consume oxygen for their survival.

The fish also require oxygen every minute, and at this time, they face oxygen shortage. Overgrowing plants will consume more oxygen and leave less amount for the fish. It ultimately results in fish death due to suffocation. 

It is necessary to maintain and control the growth of plants in the tank. Fast-growing plants require regular trimming and cutting to prevent overgrowth. Also, other slow and medium-growing ones need maintenance on time usually, per week.

Untreated and uncured aquarium plants

Pesticides and contaminants

Plants require pesticides, insecticides, or weed killer sprays while growing commercially to protect them from pests and insects. If you add them to your fish tank, they result in killing your fish.

These substances are toxic and can kill them within a few hours. Also, few chemical residues of these substances are enough to kill the fish.

It is essential to wash and quarantine these plants after purchasing as these chemicals require time to remove off. You have to give them sufficient time and treatment to make them safe for your tank.

Before quarantining, wash them with plenty of water and disinfect them. Soak them in a water conditioner and mix to remove chemical residues, leave for five days, and then place them in the tank.

Algal growth

Usually, plants are the best source to reduce algal production in the tank, but sometimes they can be a source of algae.

It happens when you add untreated plants into the tank that already have algae growth on them. This algae enters the tank, grow efficiently by consuming the tank’s nutrients. Excess algae can cause harm to fish, which ultimately leads to death.

Treat the plant before adding to the tank by dipping it in bleach solution for two minutes. You can use disinfectants other than bleach like potassium permanganate, aquarium salts, hydrogen peroxide, or alum to treat them. These all disinfectants are safe but remember rinsing the plants with plenty of water after treating them. These aquarium plants can live in brackish water.

Fungus, bacteria, and other microorganisms

Aquarium plants can also contain fungus and other microorganisms, which can be a reason to kill your tank’s fish. Whits fungus spots are prominent on the leaves that can spread in the tank causing harm to fish. Also, they may contain bacteria and other disease-causing pathogens. 

Treating and disinfection are necessary to get rid of these dangerous organisms before adding them to the tank. Soak in boiling water or any disinfectant for some time to make them safe for the aquarium. You can leave aquarium plants in pots and your fish can play around them.

Predators and snails

The parasites usually reside on plants and can come into the aquarium through the plants. Initially, they are not problematic, but once in the tank, they reproduce and increase in number and are not acceptable by the inhabitants.

They are very hard to remove from the tank and eat up small fish and their eggs, you should take care of Diamond tetra fish.

Causing fish ich

Fish ich is the most common disease of aquarium fish that can infect or kill them and transmit or spread from aquarium plants. This disease can contaminate all the decorations and ornaments of your tank.

When you observe that fish is developing white spots on their body and showing lazy and less active behavior, it indicates it has ich disease. 

For treatment, you have to take out the plants and set them apart for quarantine. Salt treatment is preferable to treat the infection, and you can also raise the temperature if the plant can tolerate it.

Also, give proper treatment and care to the infected fish. Treat and disinfect the whole tank for complete eradication of the infectious pathogen.

Decay and rotted aquarium plants

Decayed or rotted plants are a potential risk for the fish and can be deadly to fish. Healthy plants absorb and neutralize ammonia and nitrates and keep the tank healthy. When a plant decays or rot in an aquarium, the ammonia builds up in the tank, and this ammonia converts into nitrite and results in harm. 

Ammonia build-up is not toxic as it allows beneficial bacteria to grow, but nitrites are toxic. If you do not maintain the nitrites level in the tank, it leads to fish death. Also, decay leaves to release the carbon and nitrogen stores and if their levels exceed, can harm inhabitants. You will also observe the build-up of mulm that gunk-up the substrate.

Take care of your aquarium plants and provide them sufficient nutrients and light to remain healthy. Remove the decay and rotted plant parts daily from the tank and throw out all the dead leaves and debris floating in the water.

Too many plants in a tank

Plants are the beauty of a tank but adding too many in a single tank is not safe for your fish. Excess of anything is not good so are plants. More plants take more space in the tank, resulting in less space for fish to swim and play.

The fish can not stay or rest in one place, it has to move around, and if you do not provide it sufficient space to swim, it will die of stress.

Also, plants produce oxygen during day time by consuming carbon dioxide, but the process reverses at night. They start consuming oxygen instead of releasing it and spare carbon dioxide. So the carbon dioxide levels increase, and oxygen level decreases in the tank at night that is toxic.

If your tank’s air pump or air stones are not running at night, the fish can die because of a lack of oxygen. Avoid adding many plants at a time in the tank, and keep your tank’s air pump and air stones running 24 hours to prevent your fish from dying.

Change water conditions and chemistry

When you introduce aquarium plants in the aquarium, they change water chemistry. Usually, this change is not harmful to the fish, but sudden change can stress or shock them, especially when they are sensitive to changing conditions.

It is better to introduce a few plants at a time in the aquarium and let fish adjust according to this change for some days; Adding all at once can kill the fish.

Can plastic aquarium plants kill fish?

Plastic aquarium plants are popular nowadays for fish tanks as they require no care and maintenance and are super easy to handle. They look exactly like live aquarium plants and do not disturb water chemistry. Also, they remain shiny lifetime and are cost-effective.

A low quality and cheap plastic material can be poisonous and deadly for fish as they may be contaminated or release chemicals in the water. They do not absorb nitrites and ammonia from water, leading to a high level of nitrates that can kill fish.

Plastic aquarium plants can also damage fish because they are too hard and stiff. Plastic aquarium plants promote algae growth as they do not take up nutrients from the water, sparing them for algae.

Choosing an appropriate plastic material and cleaning and sterilizing plants is necessary to prevent them from killing fish.

List of Aquatic plants that can kill fish

Many aquatic plants can kill fish, and they are:

• Angel’s trumpet
• Azalea
• Black walnut
• Bleeding heart
• Caladium
• Castor bean
• Chokecherry
• Climbing nightshade
• Daphne
• Flowering tobacco
• Foxglove
• Holly
• Horsechestnut
• Jasmine
• Mock orange
• Red maple
• Snapdragon
• Yew