Adding fish

[Nelly]

Question: we have a new, about 180L aquarium that we have set up and cycled and we've just put in our first 5 neon tetras. We'd like to get 5 more (since I understand they do best in schools of 10 or more but the shop advised starting with less). How long should we wait before introducing another 5? Is one week enough or would two weeks be more sensible?

 

[Ceez]

they're more than likely recommending that so your tank can build up a better bioload of good bacteria. A few weeks to add more fish would be a solid idea especially since Neons don't produce that much waste and it takes time to generate more beneficial bacteria.

 

[Nelly]

Great, thank you!

 

[Colin_T]

You should also monitor the ammonia and nitrite levels because these will build up over the next month or so before coming down to 0ppm. If you add fish to an aquarium with ammonia or nitrite, you could kill those fish. So check the ammonia and nitrite before adding fish, they both need to be on 0ppm before you add anymore fish.

If you get an ammonia or nitrite reading above 0ppm, the easiest way to bring it down is by doing a large (75%) water change and gravel cleaning the substrate every day until the levels are 0ppm.
Make sure any new water is free of chlorine/ chloramine before it's added to the aquarium.

 

[10 Tanks]

Question: we have a new, about 180L aquarium that we have set up and cycled and we've just put in our first 5 neon tetras. We'd like to get 5 more (since I understand they do best in schools of 10 or more but the shop advised starting with less). How long should we wait before introducing another 5? Is one week enough or would two weeks be more sensible?

Hello. If you remove and replace half the tank water a couple of times a week, you can add more fish at any time. The nitrogen cycle is exactly this: You remove and replace the tank water before there's a build up of dissolved fish waste in the water. You don't have to wait until the bacteria colony becomes established. You do have to keep the number of fish to an absolute minimum and not feed those fish you have too much food.

10

 

[GaryE]

The pre-test kit trick was to add about 6 fish, as your store suggested. Do weekly water 30-50% changes (my approach is different from 10 tanks'), and 2-3 weeks later, add a few more fish. It's risky because you aren't quarantining, and the new fish could arrive ill and kill the lot.
The water routine continues, as it should for as long as you have fish in the tank. Weekly water changes matter, a lot.
2-3 weeks later, if the tank is large enough, you can add again.
If you go to an online stocking calculator, check it closely, and never exceed 75% stocking.

What I'm suggesting is heresy in some circles, and no doubt will draw fire from people who prefer the fishless cycle method. You're already on the road with a fish in cycle, so stay the course and proceed slowly. The important thing is to manage water quality so the fish are not harmed by the cycling process. In a few months, especially if you opt for live plants, you'll have a beautiful smoothly running tank that needs the fish fed and 30% water changes weekly, and otherwise runs itself.

 

[Nelly]

We have done a fishless cycle. The tank was set up just over a month ago and we were adding ammonia and the water test showed ammonia and nitrite levels at zero before we got the fish. We did a water change before adding them as well.

 

[Nelly]

We also added bottled bacteria and some of the filter media from the tank we'd set up to keep our two remaining snails in before adding them to try and get as many bacteria in as possible to give it a start.

 

[Ceez]

We have done a fishless cycle. The tank was set up just over a month ago and we were adding ammonia and the water test showed ammonia and nitrite levels at zero before we got the fish. We did a water change before adding them as well.

When you tested did you also test for nitrate? If so what did that test show?

 

[Nelly]

Yes, we did, the nitrate was low but there are plants in the tank.