Sluggy Guppy

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Aquarium Advice Newbie
May 3, 2023
So my female guppy since this morning, has been extremely sluggish, hardly moving for anything and looks extremely sick.
I did a water change yesterday and dosed seachem excel for the first time (which caused my hornwort to die overnight), since then I had a cardinal tetra die overnight and this guppy has been extremely sick. Other tank mates look alright.

My parameters have gotten weird since the water change as well. Ammonia 0, nitrite 1ppm, nitrate 0-10ppm

I took some pictures of some red spots on the guppies bottom, near gravid spot. Can anyone help me out on how I can save this guppy, i gave her a small salt bath this morning and just now put her back in the tank. Kept her in a separate container for around 3 hours.


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Nitrite is to high and will be causing health issues with your fish. You need to do a 50% water change ASAP to get it no higher than 0.5ppm.

You arent cycled. Do you know how to cycle tank?

Can you give some more details about the tank? How long has it been set up? What size tank do you have, what filtration? What fish and how many? A photo might be helpful.
So, the tank was cycled till yesterday, its been setup for 2-3 months now. Till yesterday, i decided to do a water change because it had been 2 weeks since 1 and i was going to start seachem excel.
Yesterday the params were 0 ammonia 0 nitrite 20 nitrate

With the water change, i didnt touch the filter, or anything else. Just removed water, vacuumed substrate just a little. Took out heater which had a lot of BBA, put it inside seachem excel for 5 minutes, and put it back in the tank. Everything else was similar to all other water changes i do, around 40-50%, biweekly, tap water with water conditioner (top fin).

Stocking :
(Mainly small sizes of most fish)
185gph internal filter
78 F temp (changed water was matched to temperature)
Black sand substrate, with no fertilizer
Had : 11 cardinal tetras, 11 guppies (1 fries), 10 mollies (mostly juveniles, 2 fries) and some ramshorn snails
Ph 6.8 - 7
Carbonates 80
Total alkalinity 80
Total hardness 75
Cl2 0
(Im using a strip test, i know not entirely accurate but was easy to get and good enough for ballpark)
Ammonia 0 with separate ammonia tester.

P.s, i thought 0.5ppm was for ammonia? My water tester says the nitrite is within tolerable amounts (ok its within red, and there is a bit of bactera bloom too), would it be safe to do another water change? Considering this was caused by one yesterday?

Plants :
Guppy grass
Xmass moss
Jungle val
Blyxa japonica
Java fern

Was going to add seachem excel because i had BBA growing on the heater, and heard it was good to get rid of that. Also heard that jungle val is sensitive to it, so i took out heater and dipped it inside the seachem excel instead and then dried it and put back into the aquarium.
Pictures :
1st pic from yesterday
2nd from today

On a side note, fish are acting much weirder than usual as well


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Excel is glutaraldehyde. Glutaraldehyde is commonly used for disinfecting medical equipment. It is toxic to fish, so you have to be very careful not to overdose. This commonly happens when used to kill off algae which requires a deliberate overdose.

In an aquarium, glutaraldehyde acts as a mild algaecide. It provides no CO2 at all. The algaecide properties keep the leafs a little cleaner so they can take up CO2 from the water a little easier. Given you are adding a toxic substance into the water, is it really worth the risk given the dubious benefits?

I would also say that test strips arent really good enough to give a ballpark.

No, nitrite is just as toxic as ammonia. At low pH it is more toxic than ammonia. 1ppm of nitrite will be causing nitrite poisoning leading to damage to internal organs. You should aim for ammonia + nitrite combined no higher than 0.5ppm. So 0.25 + 0.25 or 0.00 + 0.5. Whatever happened to your fish, something has crashed your cycle and you need to recycle the tank.
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Done a bit of reading around on the subject. Overdosing seachem excel often accompianies nitrite spikes. This is due to it causing reduction of O2 on the water and inhibiting the nitrogen cycle.
Oh, i guess the seachem is the problem then.

Which again has me weirded out, because i didnt add any seachem excel directly to the tank, used a separate plastic bag and just dipped the heater inside it for a few minutes, took it out, peft excess to drip and then in the same plastic bag, poured some tank water in, to wash off the seachem excel and then put it in the tank.

The only other solution i found for BBA was to use h2o2 and yaaa, i wasn't going to use that, was hoping seachem excel would be safer. Sadly the BBA is unaffected and might have actually grown.

I'm getting a lot of conflicting stuff online, regarding doing another water change or not. But just in case, i did do another small water change, this time only around 15%.

Do you have any idea what the red spots on that guppies bottom could be? She's still laying on the ground and not moving much. But she seems to be better than before, not breathing as rapidly, and is moving to hide a bit more. Another female guppy decided to give fries.

Sadly, i don't have any seachem prime on me to fight the ammonia. And i guess I'm going to have to recycle the tank :-/, not looking forward to that
A 15% water change is practically useless. If your nitrite is at 1ppm then a 15% water change will reduce it to 0.85ppm which is still at toxic levels.

I would also advise caution on using seachem prime to control ammonia, nitrite or nitrate. There is zero evidence beyond anecdotal that it does this. Its a common discussion in the hobby whether it detoxifies anything. In fact if you read the FAQ on their website they readily admit that they have no idea how it detoxifies nitrite or nitrate, if in indeed it does, and even though they claim to know how it detoxifies ammonia they wont disclose this knowledge. The only way to be sure that you are removing ammonia and nitrite in an uncycled tank is to replace the contaminated water with clean water. By all means use prime as a safety net, but dont rely on it on its own.

We are far from sure that the water change caused this.
Hmm alright thanks

I'll try to do another water change tonight. What else would you recommend?
Ya i wont be using seachem excel anymore, that was the only difference from my regular water changes. I'm hoping they start getting back to normal soon. But its gonna suck to recycle the tank again.
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