Fish It Egg Machine? The Real Answer

The phrase “Fish it egg machine?” is almost certainly a mishearing or typo of “Fisher & Paykel washing machine,” a common New Zealand appliance brand. If you actually meant “Does a fish lay eggs?” the answer is yes—most fish reproduce by laying eggs, though a few species give birth to live young. This article explains both interpretations, focusing on the egg-laying habits of fish and clarifying the washing machine confusion.

Formula

The calculator estimates how many fish hatch from a batch of eggs, given the number of eggs, the incubation period (days until hatching), and the survival rate (percentage of eggs that successfully hatch). The formula is:

Hatchlings = Eggs × (Survival Rate / 100)

Hatchlings per day = Hatchlings / Incubation Period

• Eggs – total number of eggs laid (unit: count)
• Incubation period – days from fertilization to hatching (unit: days)
• Survival rate – percentage of eggs that actually hatch (unit: %)
• Hatchlings expected – number of fish that emerge (unit: fish)
• Hatchlings per day – average daily hatch rate (unit: fish/day)

Worked Example

Using the default values from the calculator: 1000 eggs, 7 days incubation, 10% survival rate.

1. Convert survival rate to a decimal: 10% = 0.10
2. Multiply eggs by survival: 1000 × 0.10 = 100 hatchlings
3. Divide by incubation days: 100 / 7 ≈ 14.3 hatchlings per day

The calculator shows 100 hatchlings and 14.3 hatchlings per day (rounded to one decimal).

Why Do Fish Lay Eggs?

Fish are primarily oviparous, meaning they reproduce by laying eggs that develop outside the mother’s body. This is the most common strategy among the over 30,000 known fish species. Eggs are fertilized either externally (females release eggs, males release sperm into the water) or internally (males fertilize eggs inside the female before laying). External fertilization is typical for many bony fish like salmon and goldfish, while internal fertilization occurs in some sharks and guppies.

The number of eggs varies wildly by species. A single cod can release millions of eggs in one spawning season, while a clownfish may lay only a few hundred. Egg size also varies, from tiny 1 mm eggs to larger ones in species with parental care. The trade-off is simple: species with high egg numbers rely on sheer quantity to survive high predation, while those with fewer eggs often guard them or give birth to live young.

How Fish Eggs Develop

After fertilization, fish eggs go through several stages:

• Cleavage – the fertilized egg divides into many cells.
• Gastrulation – cells reorganize to form the embryo’s body layers.
• Organogenesis – organs like the heart and eyes form.
• Hatching – the embryo breaks out of the egg using enzymes or physical movement.

Incubation time depends on water temperature and species. Tropical fish eggs may hatch in 24–48 hours, while salmon eggs can take several months in cold water. Warmer water generally speeds up development, but too warm can reduce oxygen and kill the eggs.

Common Mistakes in Estimating Hatchlings

People often overestimate how many fish they’ll get because they ignore the survival rate. In the wild, survival from egg to hatching is often below 10% due to predation, fungus, and poor water quality. Even in a controlled aquarium, not all eggs are fertile. A common error is using the total number of eggs as the expected hatchlings, which can be 10–100 times too high.

Another mistake is mixing up units. Incubation period must be in days; if you have hours, divide by 24 first. Survival rate must be a percentage (e.g., 10 for 10%), not a decimal (0.10). The calculator handles this automatically, but when doing manual checks, always verify the conversion.

Live-Bearing Fish: The Exception

Not all fish lay eggs. Some, like guppies, mollies, and many sharks, are viviparous—they give birth to live, free-swimming young. These species fertilize eggs internally and the embryos develop inside the mother, receiving nutrients either from the yolk or directly from the mother’s body (in some sharks). This strategy is less common because it limits the number of offspring, but the young have a much higher survival rate since they are born fully developed.

A middle ground exists: ovoviviparity. In this case, eggs hatch inside the mother, but the embryos rely solely on their yolk sac, not on maternal nourishment. The mother then gives birth to live young. This occurs in some aquarium fish like platies and swordtails.

How to Use the Calculator in Real Life

Aquarium hobbyists can use this calculator to estimate how many fry (baby fish) to expect from a breeding pair. For example, if your angelfish laid 300 eggs and you know the survival rate is around 20% in a community tank, you’d enter 300, 20, and the incubation period (about 3 days) to get 60 fry. This helps plan feeding and tank space.

In aquaculture, survival rates are often higher (50–80%) because conditions are controlled. The calculator can also be used for educational purposes, such as estimating hatch rates in a classroom project. Remember that survival rate varies with water quality, temperature, and parental care; the calculator gives an estimate, not a guarantee.

Frequently Asked Questions

Do all fish lay eggs?

No. While most fish are oviparous (egg-laying), about 2–3% of fish species are live-bearers, including guppies, mollies, and some sharks. These species give birth to live young after internal fertilization.

How many eggs does a fish lay at once?

It varies enormously. A female cod can lay up to 9 million eggs in a single spawning season, while a clownfish lays only 100–200 eggs. The number depends on the species, size, and reproductive strategy.

What is the survival rate of fish eggs in the wild?

Typically very low, often less than 10%. Many eggs are eaten by predators, infected by fungus, or fail to develop due to poor water conditions. In controlled environments like hatcheries, survival can exceed 80%.

How long do fish eggs take to hatch?

It depends on the species and water temperature. Tropical fish eggs may hatch in 24–48 hours, while cold-water species like salmon can take several months. Warmer water generally speeds up development, but extreme heat can be lethal.

What does “Fish it egg machine?” mean?

It is almost certainly a mishearing of “Fisher & Paykel washing machine,” a New Zealand appliance brand. If you meant to ask about fish reproduction, the answer is yes—most fish lay eggs, but some give birth to live young.

Can I use this calculator for live-bearing fish?

No. This calculator assumes eggs are laid and hatch outside the mother. For live-bearers, you would instead estimate the number of fry based on the mother’s size and age, which is not covered here.

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in eggs | Number of eggs | eggs | 1000 | 0
in days | Incubation period | days | 7 | 0
in survival | Survival rate | % | 10 | 0
out hatch | Hatchlings expected | fish | eggs * (survival / 100) | 0
out per_day | Hatchlings per day | fish/day | (eggs * (survival / 100)) / days | 1