Hi Danny.

Could you fill as many of this questions out first? It will help us help you hopefully

1. How big is your tank:  Gal / litres

2. For how long has the tank been set up:

3. How many fish:

4. What kinf of fish:

5. What are the water parameters:    Ammonia.........ppm
                                                            Nitrite..............ppm
                                                            Nitrate.............ppm
                                                            pH..........................
                                                            Temp...............degrees Celsius / Fahrenheit

6. How often do you perform water changes:

7. How big are your waterchanges:      .....................%

8. What kind of waterconditioner are you using:

9. Do you add beneficial bacteria:

10. Symptoms your fish is showing:

11. Since when does your fish show these symptoms:   

12. How is the normal behaviour of your fish:

13. How do the other fish behave:

14. Post pics of the sick fish:

I don't know if the actual issue is the fact that he won't open his mouth, I think there may be something else that is wrong like the fact that he is barely moving. It sounds like he is stressed which is probably caused by poor water quality. Is he eating?? Please answer those questions, he may have some sort of bacterial infection or parasites. Is disease safe actually a form of medication? Or more of a preventative? What does it say on the bottle?

So he lives in a 1-2 gallon tank?
Too small no wonder he got sick..

IVe Worked out that its 11 litres, i Know thats small but as you said the petshop said thats all i needed, it is quite a small fish, We used to have a good filter but i used to have a really st*pid fish who always managed to find a way to get stuck in that thing. Ill try everything you said and if he survives i'll do the 50percent water changes.

It's 6 litres, I did a conversion on the internet. Unless there is different pints   Not that 11 is any better. After 6 years he is still small? Well that isn't right. And no filter? The pet shop is wrong, simple as that! That is why your fish is sick. Please don't justify it, instead just work to getting it better. Are you able to get a new tank in the next few days? I still don't understand how a fish gets stuck in a filter   I would say that fish wasn't st*pid but sick aswell making it very weak.

The most vital thing is the bigger tank, a fish won't get better unless it is in perfect water, a goldfish in a 6 litre tank does not have perfect water!

Sheesh, just come on this thread and I am cringing.... poor little fishie.

6 litres, a bowl sized tank, NO filtration... I wonder that Gerald made it for that long, no room to swim, 100% waterchanges every 2 month, no chance to ever have a cycled tank and no test kit for checking the water chemistry..... shudder... waterchanges should be done EVERY week and about 50% adding conditoner and beneficial bacteria, and if need pH adjuster

Annyway, Danny, welcome on here, glad you found us.

All already mentioned by the other members on here, I just wanna emphasize the importance;

Here's what you need:

Bigger Tank ASAP as Nossie mentioned, look out for those complete kits and get Gerald a 60-80 l tank ( incl. gravel, filter, lights )
Life plants
Airstone and pump

Most important: API MasterTestKit for Freshwater ( contains tests for Ammonia, Nitrite, Nitrate, pH )
                          Prime ( waterconditioner to remove Chlorine, Chloramine and heavy metals from tap water as they are very     
                                     toxic  to fish )
                          Stability ( beneficial bacteria to aid in the Nitrogen Cycle ) but also to prevent "New Tank Syndrome"

                          Varied foods, aslo frozen ones like Brine Shrimp, Bloodworms, Veggie Cubes not only staple food ( you don't
                                       wanna feed only one type of food all the time )

Your pet shop peeps HAVEN'T GOT A GLUE they were interested in the almighty buck, sorry to say... but we all had this experience in the past and stil have it now.

Xmas is just around the corner, almost at the front door... what about getting Gerald the best Chrissie present ever? A lovely new home, where he can move around and swim, play and explore.

All the Best

LOOOL you're right, I think it's me and my flu.... it should be clue, right? hahahahaha

Everyones still sleeping I almost blew up from not trying to laugh!