Lost 5 guppies in brand new tank - what to do next

[Naughts22 94]

The nitrogen cycle IS very confusing at the beginning, but after a few tries to get your head round it something just clicks. I had to YouTube videos by BigAl and Cory because I don’t have a scientific brain and some authors assume everyone can think like they do.

I relate to the purchase regrets but that is short lived once you have good advice.

I don’t think anyone here would recommend livestock from a big box store but sometimes you get lucky.

Also, there are few here who recommend a deliberate fish-in-cycle. Why risk it? But accidental ones like yours can work if you prioritise the fish. To me that would mean daily water changes to keep the fish comfortable, as well as very little feeding and lots of floating live plants.

 

[JCinPA1]

04/27/26 11:00 a.m. EST

Well, my little Dumbo Ear guppy seems healthy and thriving. I'm in for a long slog cycling the tank with him, but I'm glad he looks good. He's very active, swimming all over the place and does not hide much now. He's more apt to zoom through the log decor rather than sit inside it. He's eating well. And I saw my first little string of fish poop, so he's digesting well, also. Tank is still cloudy, but it does not seem to bother him at all. Measurements today:

PH: 7.4
Ammonia: 0.25
Nitrite: 0
Nitrate: 0 - 0.5
Temp: 77.4F

Although it will take over a month, I am hopeful I can cycle the tank with this one-inch fish without harming him. As I understand the process, I may as well just test for ammonia and nitrites to make sure the environment is safe for him. I'm not going to see any nitrate for quite a while, and the PH won't change much. Let me know if I'm wrong about that.

 

[JCinPA1]

05/03/26 11:30 am EST

Ammonia: 0.25 ppm

My one guppy looks fine! Have not dosed Prime in 48 hours. Am going to add some Tetra SafeStart this afternoon. I’m stopping with the Prime dosing. I overfed a bit now. I’m hoping the SafeStart will help jumpstart the bacteria colony. I still don’t want to add any more fish (wish I had started with a fishless start), but I’m getting more optimistic my one little guppy will thrive in this 10 gallon for a couple weeks.

I only tested for ammonia today, all levels are so low, and he’s so small, it’s not likely worth testing other stuff for a bit.

 

[bgarthe23 40]

Well…..here is a spot to make note of the need for testing in general. Your .25 ammonia I’m guessing is TAN (total ammonia [NH3….the bad stuff called free ammonia…and…NH4…the ok stuff called ammonium] ). Knowing your tank water pH and temperature can determine what the ratio is of each firm and thus assure one of the levels of safeness for the fish. I don’t have this memorized, but look it up on charts when needed. My gut tells me your .25 is ok, but knowing for sure helps me sleep at night. If your test is for TAN, you can get a Seachem test for just NH3 if you’d like. Seachem also makes an Alert Tag for NH3 that goes in the tank 24/7 and will indicate if the bad stuff is present and to what degree.

 

[Essjay22 137]

This calculator works out how much of the API ammonia test is toxic ammonia , NH3, and how much is the less toxic ammonium, NH4. Just enter your test reading, pH and temp, set salinity to zero and 'calculate'. You need the number in the 'NH3 concentration' box.

Free Ammonia Calculator

Aquarium calculator; Estimate the free (un-ionized) ammonia (NH3) concentration, given the total ammonia concentration.

www.hamzasreef.com

 

[bgarthe23 40]

Thanks Essjay. That is easier than looking at charts via my old school ways. If people have an easy means to check this stuff, they’re more likely to.

 

[Essjay22 137]

I had those charts saved on my laptop. Then TwoTankAmin put that link in his 'fish-in cycling part 2' article, so I saved the link instead and deleted the charts

 

[JCinPA1]

Yikes. It keeps getting more complicated. I'll deal with all that later, I can't think about it now. Grandson just left. He loves the guppy!

05/03/26 4:30 pm EST

Fish still looks great! API ammonia reads between 0.25 and 0.5 PPM. I just dosed with 35 ml of Tetra SafeStart. I'm pretty hopeful I'll get through this with this little guy thriving.

 

[bgarthe23 40]

Hope so

 

[JCinPA1]

@bgarthe and @Essjay Thanks for that info! After coffee this morning. Based on my numbers and using that calculator webpage, my NH3 is about 0.0045. I'm reading about this, too. This has been such an informative site, I just subscribed to be a supporting member, wonderful place.

With one, one inch guppy in a 10 gallon tank, I doubt I'll really get much in the way of dangerous stuff. And hopefully the dose of Tetra Safesart will be added insurance and help speed up the cycle. I notice that the Tetra site says you can add fish "Right Away!". I wonder why they would advocate that when doing a fishless cycle with added ammonium chloride and Safestart might cycle a tank in 2-3 weeks when you can safely add fish?

Honestly, it's not that hard to wait a couple weeks. I don't get it.

 

[JCinPA1]

Now, after my second cup of coffee, I re-read this article, which I found last night but could not grok it, I was too tired. Reading the above, using the calculator, and now reading this again, it all clicked into place for me. Good resource! I love his siphon analogy.

Ammonia Management - Seachem

 

[Essjay22 137]

This is from TwoTankAmin's fish-in cycling article

Your goal is to allow the total ammonia to rise as high as possible as long as the NH3 content does not get to .05 ppm using that calculator.

Your NH3 concentration from the calculator is well below that.

 

[JCinPA1]

05/04/26 9:30 am EST

Fish still looks great, good appetite, and processing (pooping) well, very active. I dosed with the Tetra Safestart yesterday, hoping it speeds the cycle, but this little guy won't likely create enough waste to rapidly grow the bacteria colony. Measurements this morning.

Temp: 77.4 F
PH: 7.4
Ammonia: 0.25 (NH3 calculation 0.0036)
Nitrite: 0 - 0.25
Nitrate: 0 - 5 (base rate with new tap water)

I think I will over feed a little bit to hopefully jump start the Tetra Safestart bacteria. The environment seems to be good for him.

 

[Naughts22 94]

I wouldn’t overfeed, there will be no benefit.
Remember that your 1” fish will only produce enough bacteria for the waste of a 1” fish.

When you are cycled and add more fish, the bacteria will be there and will multiply within a few days to sustain the cycle for the increased bioload. But your tank will not be ready straight away for all 5 fish with a fish in cycle.

When you do a cycle with ammonia you can add enough to sustain a full tank, so it allows you to add all the fish at once.

 

[JCinPA1]

I wouldn’t overfeed, there will be no benefit.
Remember that your 1” fish will only produce enough bacteria for the waste of a 1” fish.

When you are cycled and add more fish, the bacteria will be there and will multiply within a few days to sustain the cycle for the increased bioload. But your tank will not be ready straight away for all 5 fish with a fish in cycle.

When you do a cycle with ammonia you can add enough to sustain a full tank, so it allows you to add all the fish at once.

I disagree. Excess food is used to create ammonia to grow bacteria in a fishless cycle all the time. By over feeding him a little it can provide more ammonia for the bacteria to grow. The bacteria don’t “know” how many fish there are they grow to the amount of ammonia present.