Cycled tank, but when to stock more?

[teejay]

Hi all,



So, I've got a 90 litre Fluval Roma, reasonably heavily planted with 4 anubis (3x nana, 1x barteri), 1 large + 1 small java fern, 3 hygros, and some java moss. Had the plants in for one week. Then added two small tiger barbs, plus filter squeezings and lots of gravel from a friend's cyled tank. Also worth mentioning the plants spent a week in a cycled tank in the LFS.


I'm new to the hobby, and would do fishless now, but here we are. So, after two weeks with the barbs I got an API test kit. The reults were very good, ammo 0, nitrite 0, nitrates 20. It seems the cycle was sped up significantly by the seeding. Did some small water changes, and tested again, and results were same but nitrates had gone down to 10. So, after just over 3 weeks the tiger barbs left (they were on loan), and I got 6 Black Neon Tetras two days ago.


I just tested and the results are still good, ammo 0 nitrites 0 nitrates 15/20. However, I'm really not sure how long it would take for the increased bioload to really impact on the test results, if at all. When would a mini-cycle show up? How likly is it that it will?


This is related to the question of when I can add more fish. Am willing to be patient, but if it doesn't do any harm then I'd rather get some more on Sunday. But would only do so if I'm sure the bacteria has caught up with the 6 Black Neons.


Again, out of interest how many to add at the same time? I'm keen on adding Glowlight Danios. I would like a shoal of 8-10, but would this be too much bio-load? Problem is a) they like company, so in one sense it's good for them to get more at once (obviously not if it means they'll be poisoned), b) It's a less common fish, and would worry my LFS would run out before I could add more.


Sorry for all the info. A fascinating and challenging hobby this is, and it results in so many questions! Looking forward to hearing your wise words!

 

[BBradbury]

Hello tee...

Once the tank is cycled, which means that you've tested the tank water daily for several days and have no trace of either ammonia or nitrite. Then, you can add a few more small fish.

If you add some fish, you'll need to resume testing the tank water every day for traces of ammonia and nitrite. If your test shows a trace of either, then you must remove and replace 25 percent of the water. This will remove enough of the toxic nitrogen to keep the fish safe and still leave something for the growing bacteria.

That's the "nitrogen cycle". Test every day and change the water when needed. When you have several daily "0" readings for the above forms of nitrogen, your tank is cycled.

B

 

[Fishperson]

The tank should show the increased bioload and adjust to it completely within 10 days or so. What are the dimensions on the tank? It should be at least 24 inches (60 cm) long to house danios. As far as fish, how many you can get depends on how many you have. If you get 5 neon tetras in a tank that already has 20 neon tetras and 10 other fish, you may not see any spike. But if you get 5 neon tetras in a tank with 3 neon tetras, than you will see a spike. So it depends. But if you already have 6 tetras, than I would say get 3 danios at a time until you get at the level you want.

 

[teejay]

Thanks for your replies, much appreciated. There doesn't seem too much clarity online, in cycling guides, about when an increased bioload might show up, and how long to wait.

Yes, I was doing daily water tests when the barbs were in. After 8 days of 0 ammo and 0 nitrite I upped the bioload by adding the tetras. From your replies I guess I can conclude that I should keep doing this, testing every day, and water changing when neccesary, for up to 10 days, until I'm sure the increased bioload has been absorbed.

So I take it this rules out Sunday! By Sunday I could have had 5 days of readings saying it is cycled. But I guess this is too hasty to start increasing the bioload again, as it may have not yet shown the tetras bioload.

The tank is exactly 60cm long, so hopefully should be ok for a glowlight danio shoal. Slightly annoying that I can only add a few at a time. I worry that the shops will run out and then I'll have no way to get them to a comfortbale shoal level! Any other recommendations for small, active mid-level shoalers with a bit of personality!? And a splash of colour?!

 

[librarygirl]

I'd say as long as you get 0 ammonia and nitrite readings for at least a week (on its own, without water changes) you can add more fish. I'd be worried about the tiger barbs and the danios though; barbs are pretty aggressive and they should be in a larger group.

 

[teejay]

Thanks librarygirl. The barbs were actually just on loan, they left when the six black neon tetras were put in (took about 40 mins to catch them though!). So it will be the tetras and glowlight danios (if I can find them). So I'll wait until next weekend before going fish shopping again, and will only do so if I keep getting 0s on ammo and nitrite. Any views on how many to put in at once?