Angelfish Eggs On Heater (Help!)

Some keepers are surprised to find angelfish eggs on a heater and wonder if they need to do something about it.

Female angelfish have the instinct to find a vertical surface that holds her spawn and offers access for the male to fertilize them. Parental inexperience or conditions in the aquarium may result in angelfish eggs getting placed in less than-favorable locations.

Our experience can help you understand why this might happen and, more importantly, what you can do. Understanding the process and reducing heater placement can improve egg viability and survivability.

Some of the things we can cover that will help you regarding this issue include:

  • Do angelfish place eggs on aquarium heaters
  • Why would they place eggs on the tank’s heater
  • What you can do if your breeding pair spawn on a heater
  • Answer a couple of the most commonly asked questions on the topic

Do Angelfish Lay Eggs on a Heater

Yes, angelfish parents might select the fish tank heater as their location to spawn. An aquarium heater has a smooth surface well-suited for your female angelfish to deposit eggs in neat rows. This equipment usually sits in a semi or fully-vertical position, which angelfish instinctually look for in an egg-bearing location.

Fish tank heaters are usually placed on the back of the aquarium to keep them from blocking your view. Many keepers also sit them vertically for better aesthetics and to keep them near filters that provide water circulation. These locations sit within the defensible areas adult angelfish might select for their spawn sites.

Angelfish eggs can attach to the smooth surfaces of an aquarium heater thanks to its cement gland apparatus. This system consists of three pairs of glands in the dorsal and ventral areas. They secret a mucus that attaches them to the egg-bearing surface the parents spawned upon.

Why Do Freshwater Angelfish Place Eggs on Heaters

The biggest reason your angelfish laid eggs on a heater is lower overall water temperature. These observations concur with research showing how the temperature in the water column affects angelfish, including breeding behaviors. It shows that fish do not need a thermometer to know when it gets too cold.

If your aquarium heater is not working optimally, is poorly located, or is underpowered for the tank’s water volume, it will not heat the water properly. Those conditions may cause angelfish parents to place the spawning site on the aquarium heater because it is likely the warmest part of the fish tank.

Another consideration is available space, especially in a community tank. The female angelfish may see the heater as a viable surface if you do not provide enough vertical space with decorations, plants, or specialized breeding structures.

Angelfish laid eggs on heater in community tank

The male angelfish will have an established territory within a community tank, and the heater may be a vertical surface within its domain. Also, most keepers place fish tank heaters on back walls and corners, offering more defendable positions against egg poachers.

Things that will not influence angelfish laying eggs on heaters

We have never found water parameters forcing breeding pairs into placing eggs in specific locations, including on the tank’s heater. Clean water, proper pH and hardness, and soft currents promote fish health, but no research indicates these parameters affect egg placement.

What To Do if Your Angelfish Laid Eggs on Heater

So, what do you do if you find angelfish eggs on the heater? If you are not worried about them hatching, leave the angelfish eggs in their current location. If you want them to remain viable with the best hatch rate, you should protect them from overheating.

You need to be able to shut down the heater or remove the eggs from it. If you have a spare fish tank heater (we keep extras in case one breaks down), you can turn off the unit covered in eggs and place the other in the tank to maintain temperatures. The egg-bearing heater can be left in the tank with your angelfish pair or moved to a separate tank.

Best way to move the eggs

Removal is our preferred method for dealing with angelfish eggs on a heater. If you do not plan to salvage the eggs, the removal method will not matter. Exercise care when detaching eggs if you plan to keep them, though.

If you observe the angelfish pair over time, you will notice they will inhale eggs and spit them back out whenever they move them. A turkey baster is ideal for mimicking this process and works like you would when removing fry from a tank. It is a safer removal method than scraping with a blade, which often damages most eggs you might be trying to salvage.

Reducing Instances of Angelfish Laid Eggs on Heater

We have found the best way to eliminate the problem is by maintaining a proper water temperature throughout the aquarium.

Make sure your heater can handle the water volume within the tank, and use at least two separate thermometers that you can place far from the heating unit to observe temperatures.

You can sit most aquarium heaters horizontally in the tank, creating a less-than-ideal surface for your breeding pair. You might consider adding more vertical surfaces in the aquarium, especially in the male’s territory within a community tank. If all else fails, try moving the heater to the front of the aquarium and in the open; that provides a less-defensible position the parents will likely avoid.

Keeping Cool

If you notice your angelfish laid eggs on the heater, the female angelfish likely picked the location for a reason. You can salvage the eggs by powering down the heater or removing the eggs from the surface. There are also simple steps you can take to prevent this from happening.

Watching angelfish perform their parental duties is a fascinating aspect of keeping these South American cichlids. Comment below about your experience with angelfish eggs on a heater or other surfaces so we can help!


Is it common for angelfish to lay eggs on a heater?

In our experience, it is uncommon to see angelfish lay eggs on a heater. Angelfish parents tend to spawn on other vertical surfaces if your aquarium heating distributes an even temperature throughout the water column.

Chances are you will find eggs on a heater if it is malfunctioning or struggles to maintain a consistent temperature across the entire tank. Your breeding angelfish pair will seek the best water temperature, which may be on the heater in these cases. Keep your aquarium’s temperature at 80 degrees Fahrenheit and see if this reduces these instances.

Where do angelfish usually lay their eggs?

Angelfish lay their eggs on vertical surfaces. That can include smooth leaves on artificial or live plants, tank decor, and aquarium walls. Unfortunately, they may also place their eggs in unfavorable locations like filter components or the tank’s heater.

Make sure you provide plenty of options for egg-bearing surfaces to avoid having to relocate eggs. Conversely, if you want to remove the eggs to a separate tank to raise them yourself, add items like breeding cones or plastic cards you can remove after fertilization.