Can you cycle a tank with one fish (fish-in cycle)?

[nlifs]

Hello again,

Long story short ... I started with three platys but it looks like they came with some sort of internal parasite ... I now have one remaining female who is generally swimming around fine.  Unfortunately, I think she may have also caught whatever they had ... her poop last week was normal (solid/thick) but over the last couple of days has been white and stringy ... still swimming around and eating though.

First question - the tank is not yet cycled (although it might be starting ... ammonia is about 1 and nitrites are above zero).  Can the tank cycle with only one fish in it or should I add something like the Tetra SafeStart Plus?

Also, if I lose this last fish (which is looking likely), should I wait a week or so before adding new fish (to avoid potential further parasitic infections)?  If so, how do I ensure that I don't lose my cycle?

[lefty o]

yes, you can get your bacteria colony established with just 1 fish. id be most concerned with your ammonia level at this point.

[nlifs]

Thank you!

I'm using Prime to detoxify and will try to do a water change soon ...

Edited October 29, 2023 by nlifs

[Galabar]

On 10/29/2023 at 9:50 AM, nlifs said:

Thank you!

I'm using Prime to detoxify and will try to do a water change soon ...

Prime may work to detoxify ammonia.  However, you are better off pretending that it doesn't.  Do those water changes. 🙂

[Colu]

What I would do is test daily and do a 50% water changes when every your detect any ammonia and add a double dose of prime to help detoxify any ammonia or nitrite till they constantly stay at zero

[nlifs]

Don't you need your ammonia to go up somewhat in order to feed the beneficial bacteria?

I read somewhere that it's best to wait until ammonia is about 1ppm and then do a water change; if you do it sooner, the bacteria won't grow.  Was that not the right advice?

Another point to throw out there ... I'm mobility impaired so can't really do water changes on my own.  I have someone who can help, but it's not practical to have them come every other day.  How bad is it if I rely on the Prime and only do water changes on the weekends, for example?

[Galabar]

On 10/29/2023 at 7:12 PM, nlifs said:

Don't you need your ammonia to go up somewhat in order to feed the beneficial bacteria?

Yes, you need ammonia.  If you go with a fishless cycle, you can simply continue to add ammonia to maintain the 1ppm or 2ppm (or whatever) level that you want.  You could even add nitrite to get your nitrite oxidizers going as well.

However, you've got fish in the tank.  So, you have to balance keeping the fish healthy and having enough ammonia for your cycle.  If you have trouble with water changes, just don't change the water.  I'm going to lean towards your health over that of a single platy.  The platy you have should be hardy enough to handle the ammonia.  99.9% of aquariums have, in the past, been cycled with fish.  So, you (and the fish) should be fine.

Now, for any future tanks, I would recommend a fishless cycle and moving some of the media from your now established tank to the new tank.

Edited October 30, 2023 by Galabar

[nlifs]

Thank you, @Galabar!

I appreciate the sound advice.

[Galabar]

On 10/29/2023 at 7:26 PM, nlifs said:

Thank you, @Galabar!

I appreciate the sound advice.

No problem.  I spent many years cycling tanks with "hardy" fish in them.  So, I can't be one to complain.

Lately, I've actually just used grocery store bought ammonia and testing to bring up ammonia to about 2ppm, and then waiting for it (and the subsequent nitrite) to disappear.

Edited October 30, 2023 by Galabar