Sick GSP, send help

[mushmush]

1. pH roughly 7,2-7,6.
Haven't found an ammonia kit so can't say for sure.
Nitrites 0.
Nitrates more or less 10.
Salinity - unsure, still waiting for the hydrometer. I've added a small amount of marine salt (pre-mixed in water before adding) and it seemed to make him happier for a short amount of time.

2. Roughly 20 liter / 6 gallons. No other inhabitants.

3.Foods: Ox-heart and shrimp. (Waiting on snails to deliver)
Water change schedule: 50% once a week. Sometimes an additional 30% if there is a lot of left over food.
Water conditioner used: Easy-Life Aquamaker & Easy-Life Easy Start for boosting filter bacteria.
General labeled marine salts from the pet store nearby. Haven't got an actual brand... (Waiting on delivery for properly branded marine salt)

4. Changes the past week have been adding the medication "MEDIMOR Universal-Medikament" by Aquarium Münster. Currently on day 3.

5. Tank itself been up and running for about two months, roughly 2-3 weeks without fish. I used the Easy Start plus filter media from my cichlid tank which has been cycled and running for 7+ months with fish.


To make a long story short.
I planned to buy a pea-puffer, ended up with a GSP. I stressed out and researched as much as i could and have for a month just been trying to find out how to best care for this little guy. He is currently in a 6 gallon tank, and i am desperately looking for a bigger one every day. Small towns suck.
At the current moment he has been showing major signs that he is not well. He breaths rapidly and his whole body wobble up and down because of it. His butthole is painfully obvious and definitely not how it used to look. I haven't actually seen him poop or found any poop in the tank for about a week. He is laying on the bottom and hiding 90% of the time.
3 days ago before i started using the medicine he was barely eating as well.

Today when i woke up he was perfectly white and swimming around happily but still breathing fast, I gave him a tiny bit of shrimp since i had been worried he hasn't been eating much and later in the day did the 30% water change according to the medications instructions. After that he's been back to dark gray belly and sitting on the sand. Occasionally he'll come out and swim around with half his belly being white and the back half around his butt is almost black.

I highly suspected IP since that's a common thing and i got a general treatment started which my local pet store supplied me with. (Medimor universial-medikament)
I ordered another treatment for IP's more specifically but have not tried it yet.
I've also ordered some epsomsalt after a long day of searching the web as my town doesn't seem to have any available.

(I have videos to show for examples but i don't know how to add them.)

[mushmush]

*2. I forgot to mention i had three Malaysian Trumpet snails before the medication as it stated it would kill them. He occasionally nibbled on them but didn't seem interested.

[Pufferpunk]

Welcome!
As you know already, your tank is much too small for this fish. Please do try to get an ammonia test kit ASAP.
What exactly is the medicine you are using (ingredients) & what does it treat for?
is the fish showing any signs of IPs?
That fact he is eating at all is great! MTS are very hard-shelled & have been known to chip a puffer's teeth. Please do not feed mammal foods to your fish.
library/feeding/feeding-your-puffers/

[mushmush]

The medicine says "Treatment against most infections of ornamental fish in freshwater and marine water like:
-protozoa,eg. ichthyobodo, Chilodonella, Ichthophthirus,
-Bacteria,eg. columnaris
-fugi, eg. sapolergina

Types of quantities of active substances: 1ml medimore contains:
4.00mg Ethacrindine lactate monohydrate
2.75mg Methylthionine chloride
2.00mg Acriflavine chloride
0.26mg Methyl orange

As far as i can tell. Most of it is in german because it's an imported brand. But i asked the seller if it would work on internal parasites and he said it would.
And the pet store i got it from sold me the frozen ox-heart cubes at the same time i got him. They didn't have anything else they recommended.
I've ramshorn snails on the way, will those work? As well as the shrimp i do have?
Then as for the aquarium size, i am trying to get a deal done as of right now for a 30 gallon! Hoping it'll work out.

Signs showed: He gets a huge tummy when he eats. A bit bumpy. Goes away during the day but no poop is shown at all. He's always laying on the bottom on the sand breathing fast. Maybe once or twice a day he swims around and then goes back to sitting on the bottom.

[mushmush]

Looking at him right now he is swimming with a white belly but it looks like he wants to puke? He's been making coughing-like movements with his mouth and did "blow up" a little just now. Freaking me out When he does lay on the sand you can see the sand infront of him get pushed away by his breath or whatever to call it. I've increased oxygen by pouring the water from a cup and changed the flow of the pump to generate more surface movement because i feared that he might be suffocating.
I just don't know what's going on with him and i've really come to care for him.

[mushmush]

Here's a video example. It looks like he might have something stuck in his mouth? But he has been eating without issues so i'm not sure what it is.

https://youtu.be/iVmArE-Ra6E

[Pufferpunk]

Personally, I would not use that medication. Looks like a cure-all for everything!
See if you can get Prime water conditioner. Add 1 tablespoon Epsom salt/5 gallons for constipation. You really need an ammonia test kit!

[mushmush]

I did order an ammonia kit yesterday but since i live in a pretty small town shipping isn't the best. I couldn't find any in stores or within driving-distance.

What's your opinion on the other treatment i got? If it comes down to IPs. Have not used this but was the only other option i found.
Waterlife - Treats Gill & Body Flukes & internal worms.
Containing: Acriflavine 340mg/l
Malachite green 545mg/l
Piperazine Citrate 2040mg/l
(Also contains Formaldehyde as a stabilizer)

Any other tips on how i can help my little puffer? I feel so helpless having to wait on shipping for everything
And what's your personal opinion on what could be wrong? Is it too difficult to say without knowing ammonia levels? Or simply too many things currently not ideal for him?

[Pufferpunk]

Have you tried the Epsom salt yet? You should be able to get that at any drug store.

[mushmush]

I haven't tried it. They did not have them at my local drug store. It's also on it's way over by shipping.

[Pufferpunk]

Oh gosh, I hope he can hold out until then!

[mushmush]

So the epsom salts arrived and i mixed 1 table spoon in a cup of his aquarium water. It's been about 5 hours and he seem more lifeless now. The first 5-10 minutes after i added it he seemed energetic but he's back to laying on the bottom. I haven't seen anything actually come out of him but i can see white looking stuff on the bottom. I don't think it's left over food because i've been meticulous with taking out any left over bits and pieces

[mushmush]

*Update: Got a 40 gallon tank today! He'll move as soon as it's properly cleaned and prepared

[mushmush]

I got the ammonia test-kit today and this is how it came out.
Yellow shows 0 mg/l, lightest green 0,5 mg/l.

That's good right?

[Pufferpunk]

Looks good! How is the fish doing? Did you get the Epsom salt yet?