5 Gallon Tank Sick betta fish laying down in the bottom

Hello!
Today my betta fish seems to be sick, he’s just laying down in the bottom without moving, just breathing, and when I try to touch him then he moves somewhere else real quick, and stays laying like before. Usually when I go close to the aquarium, he goes to meet me, or when I open the tap he ask for food, but this time nothing, he doesn’t even eat. I checked the water parameters and it has ammonia 0ppm, nitrite 0ppm and nitrate 5 or 10ppm. The temperature is 76F. I have not clue of what it could be.
I bought new harlequin rasboras 3 days ago, and day before yesterday he killed and tried to eat one of them because it made it to his side of the tank (I have a 20 gallons tank with a divider and betta is alone on his 5 gallons side). I’ve been using 2ml of seachem excel for black algae every other day. The other fishes (corys and rasboras) are doing great so far. I always feed betta 1 pinch of food once a day, and about 3 times a week I give him dried blood worms. Help please.

 

How long did you have the betta for?

 

How long did you have the betta for?

Since July 2021. He’s not old

Since July 2021. He’s not old

So my betta just died. He literally got sick today and died today, and I have not clue of the reason why… pH is 7.8, by the way…
Here is his last picture already dead. The last thing he did 2 days ago was to kill 1 baby harlequin rasbora. I’ve been searching if they’re poisonous, but I haven’t found any info about it. It’s the only thing that comes to my mind that could have killed him, because nothing else was different on his routine, besides of that…

 

I'm so sorry to hear that. I sadly don't know what possibly could have killed him

 

So sorry he was very pretty. SIP.

Harlequin Rasboras are not poisonous. I have no idea what could have happened.

 

Ok not sure if I did that right as far as linking to another page/discussion here on fishlore. Long term members can correct me: just did copy/paste.

Does sound like people have run into problems with using Excel in their tanks. Some fish are fine, some react poorly.

Regardless, I’m really sorry that you’ve lost your fish friend.

Can Flourish Excel poison your fish? | Plant Fertilizer Forum | 315427
FWIW, not saying it was the Excel. But it is a question/discussion that has come up here before.

 

Ok not sure if I did that right as far as linking to another page/discussion here on fishlore. Long term members can correct me: just did copy/paste.

Does sound like people have run into problems with using Excel in their tanks. Some fish are fine, some react poorly.

Regardless, I’m really sorry that you’ve lost your fish friend.

Can Flourish Excel poison your fish? | Plant Fertilizer Forum | 315427
FWIW, not saying it was the Excel. But it is a question/discussion that has come up here before.

I had been using excel since November to kill the black algae growing on the leaves of my plants, and it did the job. I was looking for possible gill burns after reading the link you shared, and I really don’t find anything like that on the last pictures I took before he passed. Anyway I will stop dosing excel just to be in the safe side. I’m just worried about figuring out what killed him to avoid getting my other fishes kill, but so far I can’t find an exact reason thank you for your answer.

 

I think the 2ml of Excel was too much for 5g. I read a bunch of things saying 0.5ml for 5g. That could be the culprit but it may not have been either. Really couldn't say for sure. I don't use Excel.

 

I think the 2ml of Excel was too much for 5g. I read a bunch of things saying 0.5ml for 5g. That could be the culprit but it may not have been either. Really couldn't say for sure. I don't use Excel.

The fish tank was 20 gallons, but I had a divider that gave each fish about 5 gallons and 15 gallons. However, the water circulates around as 1. In order to dose something, it was 20 gallons of water. Anyways I got a bad gut feeling about excel, and it’s the only stuff I could blame so far.

 

I had been using excel since November to kill the black algae growing on the leaves of my plants, and it did the job. I was looking for possible gill burns after reading the link you shared, and I really don’t find anything like that on the last pictures I took before he passed. Anyway I will stop dosing excel just to be in the safe side. I’m just worried about figuring out what killed him to avoid getting my other fishes kill, but so far I can’t find an exact reason thank you for your answer.

It’s probably a combo of things, your betta may have had injuries behind the fight to the death with other fish that weren’t obvious and the stress plus excel or other factors might have just been too much. I personally was surprised that people had experienced hill burns and other things using the product. If/when you resume using it you now know things to look for if one or more of fish have a bad reaction to it. Again so sorry you are dealing with these issues in your tank.