Stocking a new tank

[nfras]

I am stocking a new tank and want to let the tank absorb the bio-load before adding a new batch of fish. How long do you think is best to leave between adding fish? A week? more?

[Fishguy2727]

Depends on how many fish you add. What size tank? what filtration? did you fishless cycle? What are your ammonia, nitrite, and nitrate readings? Have you added fish yet? What fish? How many? What is your water change schedule?

[nfras]

55gal tank
550gal/hr internal filtration
fishless cycled, just added 8 zebra danios 2 days ago
10-20% weekly water change at the moment
ammonia, nitrite both at 0 (haven't checked since adding fish)

[Fishguy2727]

What is the filter rated "up to"? I would wait a few days and the add a few more. It really depends on how you fishless cycled.

[Glasstapper]

I generally wait a week or two depending on if it's a school or not. If it's a school, then I wait 2 weeks. If it's just one or two fish, I wait a week.

[nfras]

For the fishless cycle I set up the tank and added a bucketful of water from another well cycled tank. The detritus that dies off plants when you add them should have been enough to cause an ammonia spike but I added a few drops of ammonia the first day just to help things along.

[kimmers318]

What you did to clone your tank may not be quite enough, I have always tried to use more than just a "bucketful of water" such as gravel and decor. And the 8 danios really probably aren't a large enough bioload for you to see the spikes you will see later as you add more fish. So, just to be extra cautious I would recommend adding fish very slowly, and start with the hardiest ones first. What other fish do you plan on stocking with? Leave at least a week, if not 2 between additions for the load to balance out, and in the beginning you probably won't notice much of a change in your water parameters, but I highly suggest you watch them closely. If you get any readings of ammonia or nitrite after adding new fish do not add anymore until the readings are again zero. Keep us posted as to how things go.

[jeffs99dime]

the bacteria that you need generally live in the substrate and filter material. (bio) the bacteria that are in the water are going to be nominal at best. --jeff

[nfras]

Sorry, when I said that I added a bucket of water I should have mentioned that it was the water that I had cleaned from the old tank, so it was water that had been vacuumed from the gravel and then cleaned the filter sponges in. It was pretty "organic".
Ammonia level of the tank after 48 hours was <0.1ppm

[kimmers318]

As long as you have ammonia and/or nitrite readings you don't want to add any more fish. What you added to the new tank will be a minimal amount of the bacteria needed since my understanding is it isn't freely distributed throughout the water, but actually "lives" on the hard surfaces of the gravel and decor etc. What you vacuumed was probably the waste and food leftovers from the gravel, and what you rinsed from the filters, although it wil contain some good bacteria, will also have loads of waste, which is why you rinse it off regularly. Your bacteria will slowly grow to handle the waste levels of current fish, and will need to catch up every time you add more fish. If at anytime in the future you see yourself getting small spikes a trick that has worked for me is to scoop gravel from an existing tank into a mesh filter bag (or clean nylon) and drop that into the new tank. Usually within 24 hours things are back to normal. Just be cautious, treat your new tank with kid gloves and you will end up with a beautiful satisfying tank that you can be proud of.