Woke up to blood in tank, no visible injury

[honeydew]

Hi everyone!

I have an axolotl, Peepo, who recently turned 3. He's always been extremely healthy, eats a large nightcrawler twice a week with a small amount of bloodworms as a treat one day.
I woke up this morning to the sound of him knocking things over in his tank and swimming erratically, so I got up to check on him and found a spot of what I assume is blood, about the size of a penny, on the tank floor.

I immediately took him out to turn him over for injuries and I can't find a thing, which scares me more. Is something wrong internally? He looks completely healthy and isn't acting alarmingly. Water is clean, perimeters good, about 65 degrees.
I attached pics of the "blood" and him in his tub at this moment!

(P.S., his gills have always been very stubby so nothing looks strange about them right now.)

 

[honeydew]

EDIT:
On closer inspection, his gills do look odd....they have red dots all around them almost as if the blood has clotted and they look a bit "fuzzy"....I'm going to run another perimeter check and replace the water again.

Also, for over a year now hes had what I assumed to be a longer, looping gill filament but now I'm wondering if it was somehow an external blood vessel, and it's completely gone now. is it possible it burst or was torn off? I've attached a picture where you can see it fairly well- it's darker red and a loop shape.

 

[John]

You can ignore the looping gill filament. The mass you saw looks like a poo to me - I would monitor him or the numerous next few days and see if he eats normally.

The gills in that left photo look reduced compared to the side-on photo. Hard to know if it's current damage or something older, or even something to be concerned about. Do you have a big filter in there? Heat stress or long-term water flow stress are the main causes of gill damage but I think it's marginal here.

 

[honeydew]

You can ignore the looping gill filament. The mass you saw looks like a poo to me - I would monitor him or the numerous next few days and see if he eats normally.

The gills in that left photo look reduced compared to the side-on photo. Hard to know if it's current damage or something older, or even something to be concerned about. Do you have a big filter in there? Heat stress or long-term water flow stress are the main causes of gill damage but I think it's marginal here.

Thank you for your response! When I took the red stuff out of the water it was kinda jelly-like, pure red and dissolved and when i ran water over it so I don't think it was poo, but can't be certain...
I have noticed his gills seem slightly thinner- I put him back in the freshly cleaned tank just a bit ago and they look much better there than they do in the still tub, and they're getting some color back. I'm not sure what would've caused any thinning- I have a hang-on-back filter and a sponge filter, but I keep a loofa attached to the back filter so that it breaks up the flow. The perimeters are good and temperature is around 65.

He just ate a nightcrawler same as usual and doesn't seem to be behaving abnormally, so I'm hoping it's nothing serious...what a scary thing to find, though!

Here's a pic I just took!