What Size Tank Do Platy Fish Need?

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Getting the size of the tank right makes a big difference to the health and happiness of your Platy fish. You’re likely to fall in love with these colourful lively little fish and then want to add a few more to your aquarium. But what size tank do Platy fish need?

As a general guide to minimum tank size for keeping Platy the tank needs to have at least a 10 gallon capacity. But there’s a difference between UK and US gallons when it comes to how many litres are in a gallon. In the UK a gallon is the equivalent of 4.54 litres whereas in the US there’s only 3.78 litres per gallon. You also need to take into account how many Platys you want to keep, whether you want to build a community tank and what happens when your Platy fish breed. Which they are highly likely to do! So what’s the best way to calculate the right size tank for your Platys’ needs? I’ve got a few tips to help you work it out.

What Size Tank Do Your Platy Fish Really Need?

Because the Platy is a lively little fish it needs plenty of room to swim around. That doesn’t mean the Platy likes to live alone though. In fact Platys like to live in groups and are happy to share their aquarium with other kinds of non-aggressive tank mates.

So before buying a new tank, or adding Platys to your existing tank, here’s a few things for you to consider.

Choosing A Tank For Your Platy Fish

It’s very tempting to choose a tank before deciding on the fish that you want to live in it. After all there’s some attractive aquariums and aquarium kits out there. It’s just so easy to go ‘Oooh that will look lovely full of fish!’ without considering the needs of the fish first.

So what’s the best way to do things?

How Many Platys Can Live Together?

Because Platys are happiest living in groups it’s a good idea to have at least 4 or 5 Platys in your aquarium. You can have a lot more Platys of course if you would like to. But 4-5 is a good place to start if you’re new to the fishkeeping hobby or you’re adding Platys to an existing aquarium.

If you’re going to keep both sexes of Platy fish in your tank you’ll need to get the male/female ratio right. This helps to prevent your females getting stressed out by the amorous attentions of the males. So if you have 1 male to every 3-4 females you will have the balance about right.

Platys are prolific breeders which means that the population of your aquarium is going to increase at regular intervals. Not all of the baby Platys (fry) will survive but nonetheless you can end up with far more fish than you bargained for. 

So you’ll need to factor in room for your new arrivals when choosing the right size tank for your Platy fish.

You can just keep one gender of Platy if you don’t want them to breed. While it is possible for an all male Platy aquarium to be harmonious there is a chance that one or more of your males will try to gain dominance over the other males. 

An all female tank is less likely to become a battleground. Although that’s not a certainty as some female Platys can be quite dominant. 

Basically it will come down to the personalities of your fish.

How Do I Calculate What Size Fish Tank I Will Need?

I’ve found that opinions vary on how to calculate how much space aquarium fish need. But there is a general guideline that you can use which simplifies things a little to start with.

• Allow 1 gallon per 1 inch/2.54 cm of fish

You do need to know how big an adult Platy is likely to be though. It’s no good judging tank size on the young Platy that you’re buying. 

You should calculate the size of the tank you’ll need for when your Platys are all grown up.

Here’s an example based on 5 Platy Fish

This kind of calculation is a great starting point but there are other things you have to take into account too. 

You’ll need to adjust the calculation if you’ve got all male or all female Platys as they do generally differ in size. 

One of my male Platy fish is almost the same size as my slightly smaller female. Which goes to show that sizes are only approximate and not a certainty.

So be generous in your calculations when it comes to minimum tank size.

Platy Fish Tank Requirements – What Else Should You Consider?

Once you’ve worked out your minimum Platy tank needs there’s some other stuff that you need to think about. 

• Because Platys are an active little fish they love to swim around at a nifty pace. So buying a long, rather than a tall tank, is better for your Platy. It will give them more room to zip about without bumping into each other or being restricted by the plants and aquarium decorations.

A wider tank surface will also be more efficient at dispersing toxic gases produced in your aquarium. Making the environment healthier for your fish.

• Platys like plenty of plants and decorations to hide in but it’s important to remember that plants and decorations take up room in the tank. It’s worth adding a few litres to your calculations to compensate for ‘lost space’ in your aquarium.
• Plants and decorations that provide hidey holes for fry are important if you want to save as many of your baby Platys as possible and you don’t have a spare tank to put the fry into.
• If you’re going to keep both male and female Platy you’ll need to allow some extra gallons/litres to accommodate your new arrivals comfortably.   

And as a final note on tank size for Platy fish there is something that I need to point out. 

Because Platys like to live in groups, are a non-aggressive but tough little fish, it’s possible to keep quite a few together and still have happy healthy fish. 

If you have experience in the fishkeeping hobby you can have your aquarium a little fuller than is usually recommended for a beginner. You will be able to rely more on your own judgement and knowledge of Platy fish rather than the calculation of inches per fish and gallons of water.

How To Add Platys To An Existing Aquarium

If you already have a community aquarium but would like to add more colour and movement the Platy fish is a great choice.

Your community tank needs to be a peaceful and non-aggressive one to allow your Platy fish to thrive. 

Platys are happy to live with other peaceful fish such as Guppies, Mollies and Swordtails and also with non-aggressive shrimp and snails. In fact there’s lots of possible tank mates for your Platys.

Again you need to take into account how much room there is in your tank. 

Calculate how many fish inches you already have in your aquarium. Allow a little extra space if some of your fish have chunky bodies rather than sleek figures.

You’ll then know how many gallons/litres you have spare for Platys.

Then use the calculation guide above to work out how many Platy fish you have space for.

If you’re experienced at keeping fish, then, as I mentioned above, you can use your own judgement and knowledge when adding Platys to your existing aquarium. Just remember to take into account the Platy fish’s ability to reproduce regularly.

Should I Quarantine My New Platy Fish Before Adding Them To My Existing Tank?

If you buy your Platy fish from a reputable Pet Store or Dealer the fish should have already been quarantined before they are put up for sale.

But if you’ve got an established tank that you’ve built up over a few years, or you are buying Platy from a new source, quarantining new fish is a good idea.

To quarantine new additions to your aquarium you will need a separate tank to keep your new fish in while you check for illnesses that may infect your established aquarium.

Keep your new fish in quarantine for between 2-4 weeks and check regularly for signs of illness and infection. 

If you do see signs of ill health then treat them with the relevant products. You can buy tank treatments for fish online and from good pet stores and suppliers.

Don’t add your new fish to the main tank until you are sure that they are healthy. You don’t want to risk losing several, if not all, of the fish in your established aquarium.