Home > Ask Our Experts > Can I Use Bottled Water in my Fish Tank?

Can I Use Bottled Water in my Fish Tank?

By: Jennie Kermode - Updated: 7 Jul 2013 | comments*Discuss
Discus Breed Breeding Ph Water Hardness


I have successfully kept discus fish for years but I have never had any luck with breeding. We live in a hard water area and even though I filter the water through peat the water is still not really soft enough. Is it OK to use bottled mineral water which is very soft in a tank containing only discus fish?

Or what other ways of softening the water are there without using RO water so that I may breed my discus?

(Mr Jack Royall, 9 September 2008)


Many aquarists try using bottled water at times, usually when they want to make the water harder, but there can be several problems with it. As an experienced aquarist I'm sure you'll understand the importance of checking all the parameters of the water you add, but just to clarify the matter for other readers, mineral water often contains salts which can upset the balance of your aquarium. Never use mineral water with any additional ingredients and never use carbonated mineral water (even after it's stopped being visibly fizzy). If you do use mineral water, leave it to stand overnight first with an aquarium antibiotic added, as bacteria can grow in it after bottling.

If you add soft mineral water to your aquarium you should do so very slowly, mixing it with other water, aiming to stabilise the water hardness at a lower level without rapidly changing the pH. Your peat filtering won't have been lowering the pH because of the quantity of dissolved minerals in your water, but once you start to reduce these it will take effect. You'll need to gradually reduce the amount of peat you're using to stabilise the pH where you want it.

A simpler alternative to using bottled water is using a filter system such as Aquarium Pharmaceutical's water softener pillow. This will sit in your filter system and filter out dissolved minerals at a steady rate, making it much easier to maintain the right balance.

Bear in mind that you may not need to soften the water much in order to have an effect on your discus. They'll respond to the change as much as to the acidity itself. If they still seem reluctant to breed, it may be because they don't have enough room - discus need a lot of space to feel secure about breeding. Try arranging rocks and plants to create more privacy and more secluded spaces.

Finally, you should note that discus sometimes don't breed because they just don't happen to find each other attractive. This is unfortunate, especially if you have a sizeable group, but it does happen. Like humans, discus are picky about their mates and they tend to form lasting pairs. Softening the water may make them more frisky, but it's not guaranteed to make them take an interest in each other.

You might also like...
Share Your Story, Join the Discussion or Seek Advice..
Why not be the first to leave a comment for discussion, ask for advice or share your story...

If you'd like to ask a question one of our experts (workload permitting) or a helpful reader hopefully can help you... We also love comments and interesting stories

(never shown)
(never shown)
(never shown)
(never shown)
Enter word:
Latest Comments
  • Bob
    Re: Dealing with Bullying Between Fish
    Hi. Would like some advice,I am having to take out a male swordtail,as it is bulliying the other two swordtails,who are…
    10 September 2020
  • Lee
    Re: Dealing with Bullying Between Fish
    Hi, I'm hoping someone can help. My elliotti cichlids bred not long ago and I left them to raise the babies by themselves.…
    16 August 2020
  • Ruthie
    Re: Dealing with Bullying Between Fish
    Hello, I am taking care of my Dad's fish since he passed away back in January. I know how to clean the tank and such…
    3 August 2020
  • Wteach
    Re: Dealing with Bullying Between Fish
    So, I have this big blue gourami. A couple years ago he suddenly go aggressive in chasing and forcing all the other fish…
    7 July 2020
  • Jen
    Re: Dealing with Bullying Between Fish
    I’ve got 25ltr tank with 4 betta had them for months now , they were all doing fine ... omg one started to grow so big and…
    11 June 2020
  • Lynsy
    Re: Dealing with Bullying Between Fish
    I have rwo angel fish and I've just introduced another angel of similar size and its getting bullied should I buy another…
    7 June 2020
  • Evie
    Re: Dealing with Bullying Between Fish
    I have quite a large tank with only about a dozen community fish. Just recently the only penguin fish is intimidating the…
    19 October 2019
  • Frank
    Re: Flowering Aquarium Plants
    What type of nutrients can I provid from my aquarium. Help me with name of the product
    25 September 2019
  • paris
    Re: Caring for Baby Fish
    okay i was looking in my tank this morning and found little baby fish I think they were just born maybe like a day or two ago but they are…
    27 May 2019
  • Anna
    Re: Rescue Solutions
    Its rough.. I have a dominant male African Cichlid giving me alot of grief. He was in a 55 gal tank attacking everyone so everybody started hiding…
    1 April 2019