Guppies keep dying...

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Tanktool

Aquarium Advice Newbie
Joined
Mar 16, 2025
Messages
8
Location
Fredericton, New Brunswick
Hi! I need help with my fish mystery. I've had my 10 gallon tank for a few years. Usually have 3 guppies in it but I lost my oldest ones so I had one left, wanted to get him some buddies. But every time I try getting two more, they do great for a few days, then start hanging out at the surface and swimming in the moving water only, pretty much, and eventually die within 2 weeks of getting them. I've tried adding 2 twice now, both the same result so I don't want to try again until I know why this is happening and can fix it. They don't look sickly, but they do stop eating once they start staying at the top of the water, something clearly is causing this but I don't know what. I'm not a super educated aquariest but I try to do right by my tank. I do 20-25 % water change and vaccum the gravel every week, I have a filter and an air stone. My tank isn't planted but I have an anubia and java fern living happily in there, I add fertilizer every week for them. I test my water regularly...I have no ammonia, GH of 60, KH of 80, ph of 7 to 7.5, no nitrites or nitrates. Tank is not heated, but temps are generally between 73 and 75. I do live off grid, and we heat by wood, so temps in the house do dip overnight, but I've never seen the tank temp lower than 72. I also have in the tank...two bamboo shrimp, had them about a year, seem super happy. And two african dwarf frogs, one is at least 4 years old, the other about a year. Both doing awesome. Can anyone suggest why I can't keep new guppies alive? My lone guppy seems great, albeit maybe lonely. There is some brown algae that grows in the tank, I clean it off things every other week or so. I appreciate any thoughts or ideas, thanks for reading!
 
How do you acclimate the new fish? What it sounds like is the new fish are the problem and the water they are coming from is much different from your water so they are not adjusting to it. Unfortunately, Guppies have become more fragile than in the past and prone to having multiple pathogens that become active when the fish are stressed. I'd also check with your fish source to see what their water parameters are. (y)
 
How do you acclimate the new fish? What it sounds like is the new fish are the problem and the water they are coming from is much different from your water so they are not adjusting to it. Unfortunately, Guppies have become more fragile than in the past and prone to having multiple pathogens that become active when the fish are stressed. I'd also check with your fish source to see what their water parameters are. (y)
Thanks! I acclimate them the sort of basic way, putting the bag in the tank so the temperatures can match, adding a bit of my tank water to the bag every half hour/hour until I release them. Usually 3-4 hours after getting them home. I wondered if it could be the fish somehow but the local Petsmart is the only place to buy live fish around here. I'll have to ask them about their parameters..
 
Thanks! I acclimate them the sort of basic way, putting the bag in the tank so the temperatures can match, adding a bit of my tank water to the bag every half hour/hour until I release them. Usually 3-4 hours after getting them home. I wondered if it could be the fish somehow but the local Petsmart is the only place to buy live fish around here. I'll have to ask them about their parameters..
Your acclimation method may be the problem. After floating the bag for 15-20 minutes for temperature adjustment, you should be adding small amounts of water every 5 minutes or so so that the water in the bag does not become oxygen depleted. When the water in the bag becomes 80%-90% new water and 10%- 20% old water, the fish can be released and the bag of water should be disposed of. Do not add the bag water back into the tank.
Another acclimation method would be a bucket and drip line. You can see the whole process here:
Guppies would be considered the same as the Neon Tetras in the video so a 30 minute acclimation should suffice.
Hope this helps. (y)
 
Your acclimation method may be the problem. After floating the bag for 15-20 minutes for temperature adjustment, you should be adding small amounts of water every 5 minutes or so so that the water in the bag does not become oxygen depleted. When the water in the bag becomes 80%-90% new water and 10%- 20% old water, the fish can be released and the bag of water should be disposed of. Do not add the bag water back into the tank.
Another acclimation method would be a bucket and drip line. You can see the whole process here:
Guppies would be considered the same as the Neon Tetras in the video so a 30 minute acclimation should suffice.
Hope this helps. (y)
Thanks for the input! I didn't think of acclimatization issues. Especially since the new fish seem happy for the first week or more before I start seeing their hanging at the surface behavior. Its often after my 1st tank clean/water change that I notice it starting. I will improve my process. Drip method seems easily doable if I get some small tubing. Also half considering giving up on guppies and getting some white cloud mountain minnows instead. Thanks so much for your advice, its very appreciated.
 
Thanks for the input! I didn't think of acclimatization issues. Especially since the new fish seem happy for the first week or more before I start seeing their hanging at the surface behavior. Its often after my 1st tank clean/water change that I notice it starting. I will improve my process. Drip method seems easily doable if I get some small tubing. Also half considering giving up on guppies and getting some white cloud mountain minnows instead. Thanks so much for your advice, its very appreciated.
What happens is the fish get stressed and that opens them up to disease. In your case, if you are saying they are doing this after a water change, it means they are not adjusting to something in the new water. You may want to change smaller amounts of water more frequently than one larger water change weekly or however often you were doing them. This way, the fish has a better chance of handling smaller amounts of whatever objects to them. (y)
 
Hi again. So I tried adding a single guppy. I did the drip method for introducing. It all went very well. New guppy seemed great, happy, eating, active. After a week, I did a small water change and vacuuming. Things seemed fine. Until Friday, I noticed the new guppy was now again, swimming in the moving water from the filter near the top. And seemed disinterested in anything else, didn't interact with my other guppy anymore. He died yesterday. I noted his gills appeared to have bled a bit too when I removed him from the tank. I tested my tank as soon as I noticed the change in him, no ammonia, no nitrates. I'm starting to wonder if there is something about my well water that isn't working for the guppies? But my lone guppy and everyone else in the tank is doing great. I'm so perplexed.
 
I would consider getting fish to suit the water, rather than adjusting the water to suit the fish. You could easily solve one problem and cause others.
 
I appreciate that take. I was just looking at the water requirements for my african dwarf frogs and bamboo shrimp also in there, who are all doing great. It seems they would not mind the water being harder too, based on what I'm reading. I do have some cuttle bone in the tank for the shrimp but I guess that is not cutting it for guppies. Funny how my previous guppies did well, and my now lone guppy seems great. I'll be thinking about what the best thing to do for the whole tank will be, and reading more. I really appreciate your input on this.
 
But they have acclimated to what you have and might not do so well if you adjust it. You are almost always better off keeping fish to suit the water, not adjusting water to something it doesn't naturally want to be at.
 
But they have acclimated to what you have and might not do so well if you adjust it. You are almost always better off keeping fish to suit the water, not adjusting water to something it doesn't naturally want to be at.
Fair. Thank you. I worry my guppy won't last but he does seem happy so far. Maybe some zebra danios, neon tetras, or white cloud mountain minnows if I can find some. At least he'd have some fish company. Hopefully not nippy company. You've been really very helpful, thank you for all your input.
 
Hi! I just came back to say I added some neon tetras to my tank and its been over two weeks now and they are all doing awesome! And providing some company for my lone guppy. Thanks so much for your help Aiken Drum. So very appreciative of you solving my upsetting mystery. I love my new tetras too.
 

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