You can tell there are fertile angelfish eggs when they maintain a translucent state, highlighted by earthy hues of amber or brown. Unfertilized angelfish eggs become opaque and white, making them easy to spot among the hundreds of eggs created during the spawn.
Years of fishkeeping experience has taught us what to look for regarding healthy angelfish – from egg to adulthood. We want to share this information, backed by scientific research and observational data, with you to improve your chances of hatching healthy wigglers that grow into beautiful adult Pterophyllum specimens.
To help convey this information, we have broken the topic down into relevant sections, such as:
- How to tell fertilized and unfertilized eggs apart
- What the behaviors of angelfish parents can tell you about eggs
- How males fertilize eggs and why they sometimes will not
- Stages of fertilized egg development
- Answers to common questions on the subject we receive
How To Tell if Angelfish Eggs Are Fertilized
If you are new to keeping angelfish, you might wonder what their eggs look like. Your adult angelfish will pair off for mating (although a female angelfish can lay eggs without a male present) and begin cleaning vertical surfaces they deem acceptable to place eggs upon, like broad leaves or tank walls.
The female will then lay eggs in neat little rows, bunched together. After she finishes, the male follows up by rubbing against these rows to fertilize them. At this stage, they all appear uniform in nature.
Each egg is about the size of a pin head and is translucent, allowing light to penetrate it. The eggs have a tint of earthy colors, like amber or brown. But how can you know which are fertile angelfish eggs?
Are They Fertile or Infertile Angelfish Eggs?
For many fishkeepers, the first thing they notice about their freshwater angelfish eggs is they do not change. Fertile angelfish eggs continue to allow diffused light to pass through them. The amber and brown colors not only remain, but they can become more pronounced as the hours of incubation go by.
The male follows behind the female angelfish laying eggs, with cell cleavage starting within 1.5 hours post fertilization. For the next 72 hours, you will continue to see development within the egg, including the egg sac and an oil globule. You will also notice a tail forming at about 24 hours after the eggs from your female angelfish get fertilized.
The yolk sac provides nourishment for the growing larval angelfish. It continuously feeds on the contents until the yolk sac becomes fully absorbed five days after the hatch.
Researchers assert that the oil globule within the egg contains solely saturated fatty acids that diminish during the larval stage. They believe it acts as a high-energy source, as lipids are twice as energy-dense as carbohydrates or proteins. Its status as a substance to increase egg buoyancy is more debatable.
Viable eggs also adhere to the spawning surface well. Pterophyllum eggs and subsequent larval stage specimens have three pairs of glands used as an adhesive apparatus. These glands slowly shrink and start to disappear within eight days post-hatch.
These visual components and biological processes can be hard to see, however. Most keepers simplify the identification of viable eggs by their semi-clear nature and earthy colors.
Angelfish behavior that indicates eggs are fertile
The angelfish pair that laid and fertilized the eggs will act in ways that show the eggs are viable.
Your first clue would be when the angelfish parents spawn. As the female deposits hundreds of eggs, the male will follow behind and rub its ventral (belly) region against them. That allows it to brush its genital papilla across the eggs, releasing sperm as close as possible.
Another behavioral clue is the adult angelfish focusing their attention on the eggs, no matter if they are in a community tank or a separate tank. They will constantly clean around the eggs and remove non-valid eggs if needed. You will also see your pet fish fanning the eggs with their fins to provide better oxygenation in the water near the eggs.
Freshwater angelfish will guard the eggs, chasing off and nipping at tank mates that get too close. It is an instinct that will improve the chances of hatching by protecting against predation. This behavior is more noticeable in a community tank compared to when the breeding pair are in a separate breeding tank.
Find out how long it takes for angelfish eggs to hatch.
Some inexperienced keepers are surprised to see their female angelfish laying eggs, even without a male in the aquarium. It is not uncommon, but all of these eggs will be infertile.
Even with a male present and actively following behind the female to fertilize, many eggs within the batch go unfertilized. These specimens quickly lose their transparency, becoming cloudy. Instead of the healthy angelfish egg colors of amber or brown, they become dull and white.
The unfertilized angelfish eggs do not develop a yolk sac, oil globule, or other parts found in viable eggs. They may become detached from the egg-laying surface because the adhesive apparatus do not develop. These eggs also lack buoyancy and sink when they come loose.
Bacteria will attack non-viable eggs, creating a fuzzy fungus that grows around them. Adult angelfish or keepers must remove these to prevent contaminating the other eggs.
Your pair of freshwater angelfish parents will also act differently toward infertile eggs. Most often, parents ingest them or allow them to fall away from the remaining viable eggs. If the entire spawn is unfertilized, the parents (or lone female) will likely abandon them within a day or so.
How Male Angelfish Fertilize Eggs
Male partners follow behind female angelfish laying eggs, appearing to rub their belly against the egg-laying surface. A closer inspection will reveal that a small fleshy tube called the genital papilla extends from the ventral portion of the body and is more slender and pointed compared to the female egg-laying papilla.
Male angelfish complete the fertilization process by rubbing the papilla across the hundreds of eggs the female deposited. It releases sperm at this time, filling the water nearest the eggs. The system may not appear the most efficient at first glance, but the large number of eggs and sperm released naturally ensure the continuation of the species in the wild.
Why Male Angelfish Will Not Fertilize Eggs
First thing first, you need a breeding pair. We have read or been contacted by new keepers wondering why their male angelfish will not fertilize the eggs, only to find out they did not have a male! If you are unsure how to identify the sexes, you can buy an established breeding pair.
Inexperience is often a factor with young adult male specimens. It happens enough in nature that research indicates females seek out experienced male fish for partners. Not only do they fertilize eggs properly, but their experience also allows them to defend and tend to eggs better.
Location can be an issue, as not all vertical surfaces are equal. If the male feels vulnerable where the eggs get deposited, it may avoid fertilization. The male may also sense that a spot is indefensible and avoid fertilizing the eggs, waiting for the next batch in a better location.
Stress can be a factor in males not fertilizing eggs. The fish may feel vulnerable in the tank due to aggressive tank mates, especially with other male angelfish present. Stress can also occur when things like water temperature are not ideal for the fish (or breeding).
Fertilized Angelfish Egg Stages
Larval pre-hatching stage
This stage will last for about 72 hours post-fertilization. Fertilized and unfertilized eggs will appear and behave as described above, and you should be able to tell the difference between them at the 24-hour mark.
If you examine the eggs closely with magnification, you might see movement within the fertile eggs. You will not notice much with the naked eye, especially if the eggs sit on a leaf or other decor away from tank walls.
It is worth noting that this is the stage where breeders will often remove the eggs and place them into a separate tank. This step prevents predation by tank mates or the parents. It also allows you to treat the water with Methylene blue or other compounds to reduce fungal infections.
After the hatch and before they become free-swimming angelfish fry, this species goes through a stage hobbyists refer to as wigglers. These larval angelfish are still developing their eyes and other internal organs. The tail and other exterior components still need to grow at this larval stage.
Angelfish in the wiggler stage still have the adhesive apparatus that keeps them connected to the egg-laying surface. They use the nutrients from the remaining yolk sac for nourishment, so you will not need to feed them yet. The wiggler stage lasts until about day fie post-hatch, when you notice the angelfish fry swimming freely in the water column.
Now You Know How To Tell if Angelfish Eggs Are Fertilized
As you can see, knowing how to tell if angelfish eggs are fertilized is simple. Fertilized eggs will be translucent with hues of amber or brown 24 hours after the spawn, while unfertilized eggs become opaque and white.
The eggs are not the only clue to fertilization; parental behavior can also offer clues. The adult angelfish will clean, fan, and defend fertilized eggs. Non-viable eggs will be eaten or discarded.
Healthy angelfish eggs contain a yolk sac, oil globule, and growing larval angelfish. Viable eggs will hatch approximately 72 hours post-fertilization, entering into a wiggler stage that lasts for five days.
We hope you will enjoy witnessing the process as your pet angelfishes care for their eggs. You might even consider getting more involved and raising them yourself. No matter what, comment so we can answer questions or discuss the topic more!
Why do angelfish eggs turn white?
Unfertilized angelfish eggs are a common reason they turn white, as they are non-viable. Being skipped during the fertilization process is not the only reason an egg can turn white. Bacterial and fungal infections from poor water parameters or nearby infected eggs and physical damage can also cause this.
What does a fertilized angelfish egg look like?
When you look at angelfish eggs with the naked eye, they have a translucent appearance with hues of amber or brown, with an oval shape of about 1.46 mm at the widest. A closer inspection may provide views of the developing larval angelfish, yolk sac, or an interior oil globule. As the hatching process approaches, you might notice a tail developing as the angelfish is about to move into the wiggler stage.
What does an unfertilized angelfish egg look like?
Unfertilized eggs will lose their translucent nature, becoming opaque and white. The unviable specimen becomes covered in fungal growth, and you can no longer see the components inside the egg with a closer inspection. One or both parents of the angelfish pair will ingest these eggs, or you can remove them to prevent issues with nearby healthy eggs.