Guppy emergency! Please help!

Hello, everyone --

I had four baby guppies in a five-gallon tank -- three males, one female. As they got bigger and the males got more excited, I got a ten-gallon for my female guppy. I moved her into that tank, and I got a second female and put her in as well. I let the tank cycle, tested the water, floated the bag, everything. But for a day or two after being introduced, the two fish would just hang at the very top corner of the tank behind the heater. I was worried, so I put the divider up in the old tank and moved them there, and they were immediately fine again.

Earlier today, I changed one-third of the water. The three males are active and completely fine, but the two females are sitting at the top again. When I had the four fish in the tank together a while ago, they never had issues with water changes. Even after I moved the original female and new female to the old tank, they were always fine with water changes. Eventually, though, they were okay.

I let the ten-gallon tank cycle for about four months, and I tried putting the two females in there again. They have been in there since this morning, and it is almost 1:00 A.M. The same thing happened: they are staying in the corner of the tank, not moving. They aren't gasping; they are just sitting there. Is this really bad? Should I move them back to the old tank? Why does this keep happening?

Thank you for your help,
Claire

P.S. I tested the water parameters and everything is fine.
P.P.S. In the picture attached, one female is resting almost vertically against that leaf. She wasn't doing this before -- she was just at the top like the other one.

Could you post the exact numbers?
They may just be stressed, does this happen with every water change?
Are the males in the tank with the females? Is the temperature the same all the way through the tank? They may be trying to stay warm if they're by the heater. Was the added water the same temp?

I tested the water a few weeks prior to adding the fish, so I can't remember the exact numbers. I will test the water in the morning, but if you think it is an emergency, I can go test it now.
This doesn't happen with each water change.
The males are in the five-gallon tank. I'm pretty sure the temperature is the same all the way through the tank because I have had the heater on all day. The added water was probably not the same temperature, but the heater would have heated everything by now.

You can test it in the morning. Its important but it can wait a few hours.

Are the fish all grown now?

@Colin_T might be able to help. It dosent sound serious but if it is he can help.

How long did they stay like this last time?

The fish on the left definitely is fully grown, but the one on the right might not be fully grown yet.
Last time, they stayed like that for a day or two before I got so worried that I moved them back to their own tank.
And yes, @Colin_T, please help!

claire’s_lil_gups said:

The fish on the left definitely is fully grown, but the one on the right might not be fully grown yet.
Last time, they stayed like that for a day or two before I got so worried that I moved them back to their own tank.
And yes, @Colin_T, please help!

Click to expand...

What substrate do you have? Is there anything different about these two tank? I missed that it was a different one so it actually might be serious.

I have a TopFin standard pebble substrate. It is the same type as in the five-gallon, just a different color.
The five-gallon is not heated, but that doesn’t bother the fish. Also, it’s a lot less clean, so maybe this clean tank is different to them or something?
I turned the light off in the tank for the night, and I left the room. I just came back and used my phone flashlight to look in the tank, and now they are zipping around? How is that?

They might be startled by the flashlight. Are there any different types of plants?

Edit: it may be nothing, so dont panic. Just making sure

All of the plants in both tanks are artificial.
They don’t seem to be startled by the light — they just seem active, as active as they should be. Is that a good sign? Do you think they just needed some darkness to adapt to their new tank?

That could be it just keep an eye on them and let us know how it goes tomorrow!

Thank you so much for all of your help. I truly appreciate it!

that's what I'm here for

@JuiceBox52,
I checked the tank again this morning and the two fish are at the top again. When I put in food, the younger one went swimming after it and seemed fine, but the older fish didn't move. Its poop is very long and stringy, and it is clear.

The older one has red gills that are slightly splayed. They have been this way for a few weeks, but the fish seemed fine, so I thought it was normal. I can't get a good picture of the gills, but here is the fish right now.

Please help! I am so worried.

I believe I found the issue.
I had tested the ammonia levels weeks ago and they were fine, so I had assumed they would not have changed because there was nothing in the tank. But I just tested the ammonia levels and it was at 4 ppm! That must be the problem, right? I immediately moved the females back to their old tank.