Simple answer… because sometimes new fish are sick!
When we buy new fish for our community tanks its really important to quarantine them in a separate tank. It doesn’t have to be anything flashy or well decorated, its better if it’s very sparce. Don’t add anything you can’t bleach!
We have a 20L tank set up underneath our axolotl tank, its visible, but not in the main view for the kids. Its easy for me to check on, but it’s not so visible that they can get attached and name fish. Never name fish until they leave quarantine!
How long fish are quarantined is up to you. Some guides say 2-4 weeks others say 4-6 weeks, so what’s the right amount of time? Personally, I ask the store how long they have had the particular fish in store before I make this decision. If they have had them come in that week, I quarantine for longer, if they’ve had them in for a few more weeks and have had no issues with any others in that tank, I will quarantine them for only 2 weeks.
Your quarantine tank needs to have a filter, suitable for the tank size, a bit of cover for fish to hide and an air stone if you possible. Substrate is optional as they’ll only be there for a while and you wont have plants in the tank. I prefer to have gravel because the type of fish I have, want the substrate to dig and forage. I don’t want them to get too stressed having a bare bottom while they wait to go into their new tanks.
If you are getting fish for a brand-new tank, you won’t need a secondary tank, they can just go straight into their new tank.
So why wait? We learnt this the hard way. We got too excited to add some new guppies to our community tank. Less than 24hrs later, one had a sunken belly. I took that one out straight away, into quarantine, but as it had been in the main tank, it was possible that all the other fish would now be sick. We rushed out and bought antibiotics and parasite tablets and had to treat our community tank, just in case. Thankfully all members of our community tank were fine, but the new guppy died by bed time, even though I did treat him too. Had I quarantined him, I would have saved the money on the treatment, saved my fish having to be treated and would have only needed to clean out and bleach my quarantine tank. Note, if this happens to you, a decent store will give you a refund if you bring in the fish and a water sample.
What if you don’t want to have a second tank? You have a few options. If you’re happy to do frequent water changes, just a tub or bucket it fine short term. At least an air stone would be a good idea to keep the water oxygenated and the water moving a little, but nothing else is really crucial.
If you really don’t want to have a second set up at all, you can put new fish straight into the community, however I would recommend adding the parasite and antibiotics at the same time and I honestly wouldn’t recommend this option. If you bring in a sick fish it could kill all your existing community fish. Not an ideal scenario.
