The Fish Guru

Goldfish and Guppies: Can They Coexist in the Same Tank?

Aquarium enthusiasts who are looking to add some diversity to their freshwater tank may wonder if goldfish and guppies can co-exist in the same environment. While these two species may look and act differently, they share many similarities, as well as differences.

This article will provide in-depth information on whether goldfish and guppies can live together, their similarities and differences, and answers to frequently asked questions. Can Goldfish and Guppies Co-Exist in the Same Tank?

Similarities Between Goldfish and Guppies

One of the first things to consider when deciding if goldfish and guppies can co-exist in the same tank is their similarities. Both are freshwater fish and are omnivorous, meaning they eat both plants and animals.

They are also susceptible to fin nipping, which occurs when fish nip at each other’s fins as a sign of aggression. If you plan on housing goldfish and guppies in the same tank, it is essential to monitor them closely and ensure that neither species is aggressive towards the other.

Differences Between Goldfish and Guppies

While goldfish and guppies share some similarities, they also have differences that should be considered before housing them in the same tank. Goldfish are much larger than guppies, with some varieties growing up to 12 inches in length.

In contrast, guppies are usually only 1-2 inches in length. Another significant difference between the two species is how they reproduce.

Goldfish lay eggs, while guppies are livebearers, which means they give birth to live young. The ideal water temperature for goldfish is around 68-72 degrees Fahrenheit, whereas guppies prefer a temperature between 72-82 degrees Fahrenheit.

The pH levels in the water should also be considered, as goldfish prefer a pH between 7.0-7.4, while guppies prefer a slightly more acidic pH between 6.0-7.0. The appetite of the two species also differs, with goldfish requiring a more substantial amount of food than guppies due to their larger size. Lastly, goldfish have a longer lifespan than guppies, with some varieties living up to 25 years, while guppies only live up to 3 years.

It is essential to consider the lifespan of goldfish and guppies when deciding to house them in the same tank, as it may not be sustainable in the long term. Do Goldfish Eat Guppies?

One question that is often asked when considering whether goldfish and guppies can coexist is whether goldfish will eat guppies. While goldfish are known to be predators and will eat smaller fish, this is not always the case with guppies.

Goldfish are more likely to eat guppies if they are hungry or if the guppies are small enough to fit into their mouth. Therefore, it is crucial to maintain a consistent feeding schedule for both species and ensure that the guppies are of sufficient size to avoid accidental choking.

Guppy and Goldfish: FAQs

There are some frequently asked questions regarding housing goldfish and guppies in the same tank. The following are some questions and answers to help guide you in your decision.

Tank Size: What size tank is required to house goldfish and guppies together? A general rule of thumb is to have 20-gallon tank space per 12 inches of goldfish and a minimum of 10-gallon tank space for a colony of guppies.

Therefore, if you want to have a few goldfish and guppies in the same tank, a 30-gallon tank is recommended. Plant Shelter: Do goldfish and guppies require different types of plants for shelter?

Goldfish tend to uproot plants, while guppies enjoy swimming through them. It is recommended to add plastic or silk plants that will provide shelter for both species.

Water Temperature: What is the optimal water temperature for a tank with goldfish and guppies? It is recommended to keep the water temperature around 72 degrees Fahrenheit, as it is a temperature acceptable to both goldfish and guppies.


In conclusion, goldfish and guppies can coexist in the same tank, given careful consideration regarding their similarities and differences. Both species need to be monitored regularly to ensure that they are not displaying any aggressive behaviors.

Their size, water temperature, pH levels, appetite, and lifespan should also be taken into account before housing them together. With proper precautionary measures, both goldfish and guppies can thrive in a shared aquarium environment.

Omnivorous Fish

When it comes to feeding fish, it’s essential to consider their dietary needs and preferences. Goldfish and guppies are both considered omnivorous, meaning they consume both plant and animal-based food.

Here’s a closer look at what each species needs in their diet to thrive in your aquarium.

Goldfish Diet

Goldfish are a popular choice for many aquarium hobbyists due to their beautiful colors and unique shapes. Goldfish are primarily fed on flakes or pellets from pet stores, though it is advisable to include vegetables in their diet for a well-rounded meal.

Some examples of vegetables that goldfish can eat are spinach, lettuce, cucumber, and boiled peas.

Pellets or flakes account for the majority of goldfish’s diet, and it’s essential to use high-quality food to ensure they are receiving the necessary nutrition.

You can also add in treats such as brine shrimp, bloodworms, or small pieces of cooked fish for variety. It’s essential to avoid overfeeding goldfish, which can lead to health issues such as swim bladder disease or obesity.

Feeding twice a day in small portions is a general guideline for goldfish.

Guppy Diet

Guppies are a small, peaceful species that can add vibrancy to any aquarium. As an omnivorous species, guppies are easy to feed and are usually satisfied with flake food from pet stores.

It’s important to choose a high-quality flake that is rich in nutrients for their overall health and growth. Live feeding is another option for guppies, and they enjoy small insects such as mosquito larvae, daphnia, and brine shrimp.

Brine shrimp is a popular treat for guppies and is available in pet stores, frozen, or as a dried product. It would be best to avoid overfeeding them with live food, as this can negatively impact the water quality in your aquarium and lead to health issues.

Additionally, avoid feeding them human food and processed or canned food.

Ideal Candidates for Fin Nipping

Fin nipping is a behavior displayed by some fish species that involves biting and damaging other fish’s fins in the same tank. While it’s not a desirable trait, certain fish species, such as goldfish and guppies, are more likely to nip fins than others.

Here’s a closer look at the decorative fins that make goldfish and guppies ideal candidates for fin nipping.

Goldfish and Guppy Fins

Goldfish have long and flowing fins that can be attractive to other fish, but also a target for nipping. Some goldfish varieties such as Orandas, Fantails, and Telescopes have fancy, elaborate fins that are more prone to damage.

Long fins, in general, attract this negative behavior from other fish in the tank. Similarly, guppies have decorative, colorful fins that can attract the aggression of other fish in the tank.

Male guppies are especially prone to damage as they have more flamboyant and elaborate fins compared to their female counterparts. It’s important to note that selective breeding has led to fancy fins in both goldfish and guppies, making them more susceptible to fin nipping.


In conclusion, it’s crucial to consider the dietary needs of your goldfish and guppies to ensure they live healthy and vibrant lives. High-quality pellets or flakes are generally suitable for both fish, with the option of adding in small amounts of live food or treats such as brine shrimp.

It’s essential to avoid overfeeding and monitor their feeding frequency to prevent health issues. Furthermore, goldfish and guppies have long, decorative fins that can be targets for fin nipping by other fish in the tank.

Due to selective breeding, these species have developed elaborate fins that increase their susceptibility to this negative behavior. It’s best to keep these species’ environment peaceful and monitor any aggressive behavior to prevent fin damage.

Oviparous vs Ovoviviparous

When it comes to fish reproduction, there are two main categories: oviparous and ovoviviparous. Oviparous species lay eggs externally, while ovoviviparous species incubate their eggs internally and give birth to live young.

Goldfish and guppies fall under these two categories, respectively. Here’s a closer look at egg development in goldfish and guppies.

Goldfish Egg Development

Goldfish reproduce through external fertilization, which means they lay eggs that are fertilized externally by a male. Female goldfish lay eggs on hard surfaces such as rocks, plants, or aquarium decorations.

Male goldfish will then follow and fertilize the eggs. Fertilized eggs have a small, visible dot in the center and a semi-transparent membrane that surrounds the egg.

After fertilization, it takes approximately 4-7 days for the eggs to hatch. The hatching process can be sped up with warmer water temperatures, gentle water movement, and low light levels.

It’s essential to keep the water quality high during this time to prevent the eggs from developing abnormalities or diseases.

Guppy Egg Development

In contrast, guppies are livebearing and undergo the internal development of their young until they are ready to give birth. Females have the ability to store sperm in a specialized organ called the spermatheca, which allows them to fertilize their eggs multiple times.

Fry, or baby guppies, develop inside the female’s body until they are ready to be born. Once the fry are fully developed, they are released through the female’s cloaca, with the entire birthing process taking only a few hours.

Unlike goldfish, there are no visible signs that guppies are pregnant, making it challenging to know precisely when they will give birth.

Ideal Water Temperature

Water temperature is a crucial factor in maintaining the health and well-being of your goldfish and guppies. Different species have varying ideal water temperature ranges based on their natural habitats.

Here’s a closer look at what temperatures are best for goldfish and guppies. Goldfish

Ideal Water Temperature

Goldfish are freshwater and subtropical species, meaning they thrive in water temperatures between 20-23C (68-74F).

It’s essential to keep the water temperature within this range to maintain their overall health and growth. Fluctuations in water temperature can lead to stress, susceptibility to diseases, and stunted growth.

It’s important to note that goldfish can survive in a wide range of temperatures, but their ideal range makes them comfortable and reduces the likelihood of health issues. Guppy

Ideal Water Temperature

Guppies are tropical freshwater species and require warmer water temperatures between 22-28C (72-82F) to thrive.

The ideal temperature range for guppies should be consistent and kept within this range to maintain their health and well-being. Additionally, warm water stimulates the appetite and digestion of guppies, meaning they will eat more and grow faster at these temperatures.

It’s essential to avoid temperature extremes in either direction. High water temperature can lead to faster metabolism and oxygen demand, stressing the guppies.

On the other hand, a low water temperature can lead to slower metabolisms, making them vulnerable to diseases and parasites.


In conclusion, understanding the differences in egg development and ideal water temperature requirements can play a critical role in the overall health and well-being of goldfish and guppies. Goldfish lay eggs externally, fertilized by male goldfish, whereas guppies incubate their eggs internally and give birth to live young.

Goldfish require subtropical temperatures between 20-23C (68-74F), and guppies require tropical temperatures ranging from 22-28C (72-82F) to thrive. Maintaining consistent water temperature and quality is essential for both species’ health, growth, and survival.

Preference for Acidic vs Alkaline Water

Water pH is one of the most critical water parameters to consider when setting up an aquarium. The pH level indicates the acidity or alkalinity of the water, with a pH of 7 considered neutral.

In general, goldfish and guppies prefer slightly different water pH levels. Here’s a closer look at the significance of pH levels for goldfish and guppies.

Goldfish Water pH

Goldfish prefer slightly acidic water conditions with a pH range of 7.0-7.4. Goldfish produce significant amounts of waste materials, which can accumulate in the aquarium and lead to high levels of harmful toxins. Maintaining a slightly acidic pH in the aquarium helps prevent the waste materials from breaking down and producing toxins such as ammonia, nitrites, and nitrates.

In addition to waste production, low water quality and pH fluctuations can result in stressed and sick goldfish. Stress from pH levels that are too high or too low can lead to weakened immune systems and the development of diseases.

Guppy Water pH

On the other hand, guppies prefer slightly alkaline water conditions and a pH range of 7.0-7.2. Water that is too acidic can harm guppies by stressing them, which can lead to sick fish and reduce their growth rate. Although guppies are hardy fish and can adapt to different water conditions, keeping the water pH within the ideal range can help ensure the fish are healthy and vibrant.

It’s also essential to avoid rapid changes in water pH, as it can be stressful for the fish and lead to poor health. Maintaining a small pH range along with consistent water quality is the key to keeping guppies healthy and happy.


Fish have varying appetites, and their feeding habits are essential to consider to maintain their health and happiness. Here’s a closer look at the appetites of goldfish and guppies.



Goldfish are voracious eaters and have a big appetite. They are opportunistic feeders and will eat almost anything, from pellets and flakes to live or frozen food.

Although they enjoy frequent feedings, overfeeding can lead to obesity, which can cause health issues such as swim bladder disease and shorten their lifespan. It’s essential to provide high-quality food in small portions distributed multiple times a day.

Feeding your goldfish two to three times a day will generally suffice while also ensuring that the food is appropriate for their size and dietary needs. Guppy


Guppies, on the other hand, are picky eaters and can be selective feeders at times.

They prefer small and frequent meals and can become stressed if their feeding habits are disrupted. Feeding guppies too much food can lead to a decrease in appetite and a slower growth rate.

It’s important to provide small and frequent meals and avoid overfeeding guppies. Besides, they require food that meets their dietary needs and contain all the required nutrients, such as amino acids and vitamins.

Flake food is an excellent base diet, which can be complemented with live or frozen foods such as brine shrimp or bloodworms.


In conclusion, understanding the pH levels that goldfish and guppies prefer and their appetite can contribute significantly to maintaining their overall health and happiness. Goldfish prefer slightly acidic water conditions while guppies thrive in slightly alkaline water.

Maintaining consistent water chemistry is essential for both species. Goldfish have a big appetite and require small and frequent feeding with high-quality food.

Guppies, on the other hand, can be picky eaters and require small but frequent meals with a balanced diet to maintain their health and growth. By providing the right food and maintaining the ideal water conditions, goldfish and guppies can thrive and live healthy and happy lives.

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