Tropical Fish Care Guide

Tropical fish are some of the most popular varieties kept as pets, with tetras, gouramis and guppies all falling into this category.

But their needs are very different from those of cold water or temperate fish, and it is vital you get everything right so they stay healthy. This includes water temperature and food, but don’t worry – it isn’t as hard as it would sound.


  • Lifespan: 3-5 Years
  • Average Size: 3.5-12cm
  • Popular Breeds: Siamese Betta, Gourami, Loach, Tetra
  • Diet: Omnivores
  • Origin: International warmer waters
  • Speciality Requirements: Temperatures 25° to 27°C


  • Your exact needs and setup will need to be fine-tuned depending on your breed of fish
  • Fish can have vet checkups but could need a specialist and you may also feel it is unnecessary
  • Their upkeep costs can be minimal, with filtering the water, maintaining the heat/pH and their food the main purchases
  • Most fish will need to live in small groups, but they will need to be monitored in terms of behaviour
  • The size of the tank they need will depend on how many there are in the group, and their size and space needs
  • The filters and temperature controls you buy will also depend on the size of the tank and of the fish
  • It is a good idea to also fill the tank with the appropriate plants and lighting based on the fish breed(s)


You can actually buy fish either online from reputable stores, or from pet shops or aqua shops. Many towns and cities will have somewhere which sells fish, although if you are after a particular breed, you may have to go more specialised.

We would usually recommend being able to visit a shop or store in person so you aren’t ‘buying blind’ and can ensure the fish you are buying are being kept in suitable conditions which should mean they are healthy.



It can be difficult to assess the health of a fish, especially if they’re a small breed. The best way is to see them in person, ensure they are all swimming actively and look to have shiny scales. Fins should be straight, gills should be red on the inside, and white spots or protuberances are bad signs to look out for.

If fish have not been kept in suitable conditions, they could already be suffering from health issues

As a general rule, if they have been kept in perfect water conditions, they should be healthy


If you buy from a reputable breeder, they may be able to tell you the rough ages of many of the fish, as they will have carried out stock assessments.

But it can be hard to age fish or try and pick out a certain age. For most fish, it makes little difference anyway in terms of behaviour, except acting as a rough guide to how long you will have them

Tropical Fish Care Sheet


This could be an important factor if you have a tank of fish and need to get the gender ratios correct to ensure there are no fights or overbreeding. It can be hard to sex a fish though, so this is where buying from experts will really come into play


Obviously, fish can’t be taken out of their tanks and handled for cuddles or taken out of the water for long.

But if you do have to transfer them to clean the tank or separate because of behaviour, nets are available as well as guides on how best to do this

Ensure that any fish taken out of their main tank are put into suitable conditions, even if it is only for a few hours



The size of their tank will depend on the size of the fish, and how many you have. You will also have to get a larger tank if the fish will still be growing over the next few months, as it is false economy to buy a tank which will be too small within such a short time frame.

You can’t buy a tank which is too big, so try to buy the minimum size needed and then go up a few sizes


Fish tanks will need a basic clean regularly, particularly the inside glass as water mixed with the lighting means algae will build up. This will turn it a horrid green colour, and mean the filter finds it harder to clean the water.

It is important to have equipment which will keep it as clean as possible in-between times, such as filters

They will need a more thorough clean, including cleaning the gravel and changing some water, between every two weeks and a month. This all depends on how many fish you have and their living conditions, so you need to keep an eye


The general water temperature for a tropical fish will be 25° to 27°C, although exact breeds will need certain temperatures. This could need to be very exact and precise, or you could have some leeway, so before you buy, you should check that your chosen breed is not too much care for you to be able to cope with


Tropical fish are freshwater aquarium fish and do best around the 6.8 to 7.6 pH level which is around the neutral point. Certain fish may need it a bit more fine-tuned, though.

It would be good to have a pH reader on your tank at all times

pH tends to fall with the breakdown of organic material over time, so it needs to be monitored regularly


When people have lighting in their fish tanks, it is usually more for the plants than it is for the fish. The animals are not as reliant on the lighting, but it can make the tank look very nice in the daytime.

Plants are more important to a tank than you may initially realise, as they play a part in keeping it clean

LED lighting is generally seen as the best option as it produces little heat – you don’t want the tank getting any warmer than it needs to be. Your exact lighting needs will depend on the breed of fish, and the plants they need.

Fish need resting time too, so there should be a period of darkness to encourage their circadian rhythm. You will likely need a timer for this


The substrate also depends on the fish type. Most tropical fish require a lower pH level than the coldwater fish, so anything involving coral will be too much. But bottom-dwellers won’t like gravel, and some breeds like to burrow so will need something soft like sand. You may also wish to have sections of some plant-specific substrate if you have specialised plants.

Search for the best substrate based on your breed.

Other Products Needed

On top of the plants that the tank will need in order to produce oxygen (O2) and absorb the carbon dioxide (CO2) and ammonia (NH3) that your fish generate, fish will probably like some houses or other decorations in which they can hide or swim around. This will stop them from hiding behind the pumps or filters in the tank

Tropical Fish Care Tips



Most tropical fish are omnivores, so will eat a mixture of greens and meat-based flakes and pellets. But each breed can have particular dietary needs and favourite foods.

Fish food usually comes in dry flakes, granules or pellets as well as frozen meats or spirulina, freeze-dried, or live foods. Some fish even love fresh greens such as leaves and cucumber. As a general rule of thumb, the larger the fish, the more likely the feeding is complicated and involves specialised feeds

Issues With Diet

Like with all animals, if your fish don’t get the correct balance of nutrients, they can become ill. Dedicated food should give them everything they need. The main issue is to ensure omnivorous fish eat both meat and greens, but herbivores eat only greens.

Vitamin deficiencies and poor-quality food can cause illnesses such as Hole in the Head, so always buy the best food you can and supplement with any extras needed

Foods To Avoid

You shouldn’t give your fish anything which they can’t eat. Stick to their dedicated fish food, and ensure it is suitable for their breed.

There are a few guides out there which give you alternatives if you’ve run out of fish food, such as rice or fresh fish, but it is best not to risk anything and keep their regular food going

Tips For Feeding

Fish owners are much more likely to overfeed their fish than underfeed them. Too much food will increase the amount wasted and the waste the fish produce, and therefore dirty the water quicker.

Adult fish should be fed once per day, or a few times if you want to split the portion sizes down. You should only give them as much as they can eat in five minutes, as a guide.

All of the food will have guidelines to follow on the packaging, and you can make slight changes based on eating habits or how many fish you have. You may wish to spread the food out throughout the tank so all fish have equal access to it, in case any are more dominant


Health Checks

Checking a fish is healthy is probably not as easy as any other animal. You should watch the tank every day to ensure they all seem to be swimming about with ease and are all still looking healthy and with shiny scales. Check they are all eating when you put the food in, and that their fins are all straight and there are no scratches or tears.

The biggest tell-tale sign that your fish is healthy is if the water is healthy, though. Keep up daily checks and make any alterations ASAP, but be careful not to make changes too sudden

Veterinary Care

Fish can have vet checkups, although it is more common with individual large fish who are presenting any issues (such as a goldfish or betta) as opposed to a shawl of small fish. You may need to find a specialist vet who will accept fish, and they can be there for advice or to take any concerning fish to

Common Issues

Aggressiveness amongst fish groups can be a common issue, and cause underfed fish or injuries. Fish Tail Rot is one disease caused by bullying, and can also be caused by poor water quality. Popeye is another

Ammonia poisoning can cause stress and other diseases for your fish, and you can tell if there is an issue if they are high in the water and gasping for air.

Cottonmouth and fungal infections can affect all freshwater fish, which is usually found by looking for pale or white spots around the mouth, and lesions on their back. Dropsy is another common illness and can be spotted by the swelling of their abdomen and loss of appetite and movement.

If you think one of your fish is ill or being bullied, you should quarantine them and get in touch with a vet. The good news is that some issues can be rectified with a simple water change, but others may need more long-term solutions – White Spot, for example, requires a big clean and water change, and a lengthy monitoring time