fishless cycled - added first fish

[houndour]

OK, tank completed cycle on Tuesday.

I did a 50% water change and added 3 corys and 3 botia on Wednesday.

I did another prob 40% water change last night (thursday).

My Nitrates are sky high still. Prob about 40-80 (its hard to tell with the scale, but it isn't below 40 yet).

Ammonia and Nitrites have been zero on Tues, Wed and Thurs.

Should I do another water change tonight?

When should I add more fish?

I was going to test for nitrites/ammonia and nitrate every day for the next couple of weeks to check if there is another nitrite spike.

 

[rdd1952]

It's too late now but after a fishless cycle, you should do a 75% to 90% change to get rid of all the nitrates. Just keep up the water changes until you get them down. There isn't any other way to get rid of nitrates. Just be careful that you don't cause a major swing in the pH with all the water changes. Check the pH of both the tank water and the tap water before a change to make sure they are reasonably close to the same. If your tank happened to have dropped to around 6.2 and your tap water is 7.2, a 50% water change would move the pH to about 6.7 which would be very difficult on the fish.

Also, you didn't mention how large the tank is. After a fishless cycle, you should add your entire stock of fish. The tank is cycled and the bacteria colony is present to support it. If you only add them slowly, there won't be enough waste produced to keep all the bacteria alive. The will die off to just enough to take care of the fish you have.

 

[houndour]

It's too late now but after a fishless cycle, you should do a 75% to 90% change to get rid of all the nitrates

Oh. I followed the article in the pinned topic:

A large water change (50-70%) should be done before adding any fish to the tank to lower nitrate levels, which can be a pain to bring down later.

My pH is 6.7 in the evenings and the water is 7 to 7.5 (the colour is nearer the 7 though). I will do the 'narrow' range test to find out exactly.

The tank is 19 UK gallons. I didn't know if I should add all the fish or not. I asked on here but different people gave different responses so I got 6 which is about half the stock. The most I would have been able to get on Wednesday was 9 (6 corys and 3 botia). The dwarf gourami were being quarantined and wont be for sale till tomorrow.

Is it too late to add more fish now? What would you recommend for a course of action? The fish have only been in there 2 days.

Sam

 

[rdd1952]

As for the sizeof the water change, either one will work. Naturally a larger one gets rid of more of the nitrates. And since the good bacteria are either on your filter media or in your substrate changing water doesn't really affect your bacteria. Since it has only been 2 days since you added the first fish, I think you would be fine to add the rest, expecially if the 6 is half. Adding 6 more Shouldn't be a problem.
I basically ran into the same problem with my 75 gallon. My cycling finished during the week. I kept feeding ammonia all week to keep the bacteria fed. I went last Friday to get my fish and NOBODY had angels and the LFS that always has the corys I wanted was out of those too so I ended up with only half my fish. I guess I will end up with a mini cycle when I finally get my angels (just check the store today and they didn't get any in again so I guess I'm waiting another week). I hope I can find the corys this afternoon. Maybe if I add the corys today and the angels next week it won't be bad.