Fathead Minnow (Pimephales Promelas): Ultimate Care Guide

Common name(s)Fathead Minnow, Fathead, Tuffy
Scientific namePimephales Promelas
OriginNorth America, Canada to Mexico
TemperatureAround 10°C to 20°C
Size2.5 inches to 3 inches
Minimum tank sizeMinimum of 20 gallons
Food & dietFlakes, pellets, live or frozen food
LifespanUp to around 3 years depending on care
Water pH7 to 7.5
Tank matesOther Fathead Minnows, similar shaped fish, Danios, Red Shiners
BreedingCommon, males take charge of care
Common diseaseEnteric redmouth disease, fin rot

The Fathead Minnow, or more scientifically known as Pimephales Promelas, is a species of the cyprinid family. They originate from North America and Canada but can be found all the way down to Mexico. They are commonly found in many small rivers and ponds and are able to tolerate more extreme conditions unlike other freshwater fish. The colouring of these fish ranges from an olive-brown colour all the way to reddish tints, while they all have a round head, large underbelly and a stripe of darker colour running from their head to fin across their side. Individuals of a more reddish tint are known as Rosy Red Minnows. They get their name from Pimephales, meaning ‘fathead’, and Promelas meaning ‘before black’ referring to their iconic shaped heads and the darker colouring of most specimens.

Fathead Minnow
Fathead Minnow

Fathead Minnow Care

Fathead Minnows are relatively easy to care for as they are able to withstand many conditions in the wild. However, it is important to ensure they don’t just survive, but are happy, healthy and thrive in their home. Their temperament and suitable conditions allow them to be a more flexible inhabitant, making them easier to look after and adaptive to your needs as well. The low maintenance levels make them perfect for all levels of experience with aquariums and for being housed with many other species to add to your current collection! Their schooling nature also makes them a perfect addition from a visual standpoint.


Fathead Minnows should be kept in a tank with the water temperature between 10°C and 20°C, and on the higher end of the spectrum if you want them to breed. Although they may tolerate temperatures above or below this, keeping the temperature between these figures is better to ensure their health and comfort stay optimum. It is important to maintain a fairly stable temperature and testing it often to ensure this, with the use of external heaters, chillers and simple positioning in a room to influence this. However, the temperature may be raised slightly, especially around the summer months to encourage and support breeding to reflect their natural habitat.

Water pH

The pH in the tank should aim to be between 7 and 7.5, slightly alkaline, and it is important to monitor this so that it doesn’t slip out of this range. This can be done using either manual or digital testing kits, both being available either online or in your local pet store. It is essential to keep this figure at the correct level otherwise it will cause chemical imbalances in the water and possibly put the health of the fish at risk. Testing should be carried out every day and if the pH has changed but the fish still seem fine, it is important to correct the pH as soon as possible anyway as this will make sure they are the healthiest they can be and have the longest lifespan as possible.

Fathead Minnow Size

The Fathead Minnow is a fairly small fish, with individuals reaching up to around 2 inches in the wild, while if treated well in captivity, they can grow upwards of 3 inches. Their size varies for each fish, but their health, treatment and water conditions will affect their growth. For example, some diseases will cause stunted growth if not treated properly and quickly. In the wild this would normally make them easy prey, however, the conditions they live in allows them escape from many of these predators that cannot survive in them. Their size also allows slightly more flexibility in terms of tank size as they may not require as large tank which may be perfect for aquarium hobbiests on a budget.

Food & Diet

Fathead Minnows are not a picky species of fish, due to the range of environments they live in the wild, they are adapted to survive off different foods, however, a varied, balanced diet is optimum for their health, so it is important to consider this. Flaked, pellet, live and frozen food are all suitable, however, certain foods such as bloodworms should be consumed less often as if they eat it too often, it may cause some adverse effects such as health complications. They are an omnivorous species so will eat both other animals as well as vegetation options. They tend to have a preference towards plant-based food so you may want to include plants they can feed on in their tank as well as manually feeding it to them. Plants should make up around 70% of their diet, with live food being an occasional treat and flake or pellet food making up the rest of it. It is also important to consider the size of the food as they are a small fish, so make sure that they are able to eat and digest it all comfortably. It may be required to cut up some foods, while packets for pellet or flaked food should be checked and compared on size. They will also eat most foods given to them regardless of the balance or nutritional value so care must be taken to ensure that they get what they need, and their diet doesn’t consist of too much or not enough of anything. If in a larger aquarium or pond, their feeding may be slightly different as it will have to be suitable for all species in the tank. Especially if there are slightly larger fish in the tank or pond, ensure that all individuals are getting plenty of food and they are not fighting over it, particularly if it is a sole fish stealing a significant amount, more than it requires.


The average Fathead Minnow will live up to 3 years in captivity with the right care, however, this number is significantly shorter in the wild, with most rarely living past 2 years. The mortality rate of Fathead Minnows is extremely low, with around 1 in 5 individuals even making it past 1 year. They are able to live a fairly long happy life as long as they live in suitable conditions, have a healthy diet and are treated for any medical problems they have. Due to the large number of spawn by mature females each year, the high mortality rate does not mean a low rate overall as there are still enough born to sustain their numbers. Their short lifespan means that although multiple generations of Fathead Minnows may be alive at once, this is short-lived and limited by how long an individual fish lasts, for example, if one fish lives to 3 years old, there may be up to 7 of their generations below them alive at once.

Tank Size

Fathead Minnows are a schooling species meaning they thrive in groups of at least 6 individuals, meaning the tank needs to be large enough to house all of them. A school of around 10 fish will require a tank upwards of 20 gallons, but the exact number will determine more exact size. They are also suitable as part of larger aquariums, meaning they may have a much larger tank. They are a small fish so a very minimum of 10 gallons may be suitable for 5 or 6 fish, however, this is the lower limit as much smaller and they will be in a group too small or not have enough room to swim around properly.

Tank Setup

The natural habitat of Fathead Minnows has been found to be shallow, muddy waters, with low oxygen levels, a lack of predators, high turbulence and a few other similar, peaceful species. The ability to survive such extreme conditions make them a very unique, interesting species, especially their adaptive behaviours. They do not have many predators as most other species could not tolerate the conditions, meaning surviving alone acts as a defence mechanism for them, allowing them to continue to populate the world well.

One of the key features of a tank suitable for Fathead Minnows should be plenty of structures at the bottom of the tank to allow males to defend and keep their spawn safe. These can be made from decorative caves, carefully placed wood or even pots as long as they are all of safe materials. It is also important to have a soft substrate to allow for males to burrow and dig around to keep eggs safe during breeding. A sandy substrate would be perfect as it is soft and reflects their natural environment well. A filtration system is also required to keep the water clean. However, a basic one will suffice as they are a fairly low-maintenance species.

Are Fathead Minnows suitable for ponds?

Due to the natural habitat of the Fathead Minnow, they are one of the best species to be kept in a pond. They are resistant to lower water qualities, have a peaceful temperament so are suitable to be with most other species and resilient against disease. The pond should be at least 75cm deep and have similar modifications as a normal tank should you wish them to breed. There should be plants and open space to allow free swimming and hiding. As they are a schooling fish, it is best to have at least 10 Fathead Minnows in the pond, but closer to 20 being optimum. The pond may have other species, so it is also important to consider their requirements. Some tank mates may also see Fathead Minnows as food due to their size, so confirm the temperaments and feeding habits of other potential fish.

Fathead Minnows have been used as mosquito control as the feed on mosquito larvae, preventing on more from hatching and due to their high reproduction rates, they can stay on top of the levels of larvae. However, they may need to be replenished as Fathead Minnows have a fairly short lifespan.


Male Fathead Minnows will develop a growth on their heads, contributing to their name and vertical stripes on their bodies. Females do not have such identifiable changes, however, they tend to be smaller on average than males, although this should not be used to confirm as other external factors will contribute to their size. It is important to be able to be tell males and females apart during the breeding months as it will determine which individuals will be aggressive, and may help you to watch out for any potential injuries from headbutting if the fighting gets extreme.

Fathead Minnows are a distinctive fish as many species eat their own eggs or take no parental care over them once born, whereas these will not only build a nest but also stay and protect their eggs until hatching to ensure their safety.

Breeding Fathead Minnows usually occurs naturally in the summer months when the water temperature begins to heat up to around 16°C. However, they will breed naturally in captivity; the results will be more successful if you control the environment and ensure they have everything they need. Fathead Minnows are a unique species in the sense that the males take the role of protecting their offspring against other males. This will cause some aggressive behaviour, including headbutting during the breeding season between both males and females. The male will create a nest at the bottom of the tank, by finding a cave like structure and sometimes burrowing into a soft substrate. These nests tend to be in shallower waters, but a tank may not allow for this, while a pond might. A mature female will then come along to spawn on the eggs, but they may have the attempt multiple times as the males are very protective. Once the female has done their part, the male will fertilise the eggs and defend them aggressively while hatching. This system allows females to spawn thousands of eggs in a year, but not many will necessarily survive as the eggs may be eaten by other mature females or the nest may get destroyed before the eggs can hatch. The process is also very demanding on the males, meaning they may turn to eating their eggs to sustain the demands of energy expenditure. After hatching, the spawn will grow quickly and will reach reproductive maturity in just 4 months. This survival of the fittest will hopefully mean only the strongest and most adapted survive, so any fish entering the tank will be able to keep up and not have to fight for their food. Over time, it will also produce the strongest males again, so the species will only develop positively and pass on the best qualities to their offspring.

Disease and parasites

Like many other species of fish, Fathead Minnows are susceptible to infections and parasites which need to be treated to ensure they stay healthy, however, they tend to be more resistant to disease caused by intolerable conditions as they have adapted to live in. This should not however be a pass to put them in conditions which don’t meet a good standard as it is unethical, will have a negative impact on the fish and will limit their standard of life.

Fathead Minnows are a known vector of the pathogen causing enteric mouth disease which not only means they suffer from the disease, but also pass it on between them easily. It can be fatal as it causes haemorrhaging of the mouth, eyes and fins, though it can be treated with antibiotics if caught early enough.

Fin rot is another common ailment affecting Fathead Minnows caused by certain strains of bacteria. However, factors such as their environment and stress can make them more susceptible. Fin rot, as the name suggests, causes deterioration and loss of fins and can be spotted early in fin colour changes. It is fairly common and therefore easy to treat if spotted early on, however, as Fathead Minnows do not have significantly large or colourful fins, it may be harder to spot and slower to treat. Suffering of this disease and many diseases in general can be managed by ensuring the tank water is clean, filtered, the right temperature and pH and compatibility with other fish in the tank is suitable to limit aggression and stress.

Tank mates

As with most species of fish, it is best to keep Fathead Minnows with either other Fathead Minnows or other species of a similar size, shape and temperament. In this case, this would be other smaller, peaceful fish. Larger species may see them as food, while if housed with smaller species, they may eat them instead. Other peaceful fish will allow a balanced tank with no fighting, other than in breeding season which may become problematic. It is important to consider that some species may not be suitable to be their tank mates during breeding season due to the sudden aggressive nature of males, especially if they have a similar pattern within their own species, meaning they will either not be suitable at all or have to be separated for those months within the year, which will also require two separate tanks and acclimation time.

Some compatible fish may be Danios, other Minnows or Red Shiners as they have been observed to get on well and have similar conditions and feeding patterns. Incompatible matches may be that of Goldfish, Tiger Barbs or Bucktooth Tetras. Aggressive and fighter fish such as the two latter would be very unsuitable as they would likely kill or eat the Fathead Minnow within days of being in the same tank together.

Fathead Minnows for sale

Fathead Minnows tend to be sold in most pet stores, though if unavailable, there is plenty for sale online. Each individual fish cost around $2.50, though you will need to consider the cost of the tank, decorations, pH testers, filtration system, food and other tank mates on top of this. Due to the regulation of the Live Fish Act (1980), any shop selling Fathead Minnows need to have a license to sell these fish and must also keep track of how many they buy and sell, so if buying from a retailer you don’t trust, enquire as to whether they have a license and proof to ensure they are both acting ethically and won’t sell you unhealthy or illegal specimens.

Are they an invasive species?

Fathead Minnows are not currently classed as an invasive species but having a secure and stable population due to their high reproduction rate and lack of some predators in the wild. However, due to their high numbers in being both bait and a common aquarium pet, they have been considered a pest in many countries and have high invasive potential should their population get out of control. They have been related to causing the decline in numbers of some native and endangered species such as the Lost River and shortnose sucker due to consuming their food resources and taking up their habitats. They pose a threat in terms of being a vector of the enteric redmouth disease as it can have devastating effects on other species which may contract it such as eels and species of trout. Its accidental and purposeful introduction in countries such as Europe is becoming worrying due to them thriving in most environments. Their threatening status has caused them to be prohibited in some parts of the world such as in Washington, USA where it is illegal to possess, buy or sell any individuals of this species.

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