The only thing is, that you need double the filter-rating for goldfish

Sorry about your fish

What happened with your filter? As you've mentioned fish getting trapped before?
Maybe you could cover the inlet with the foot of some new tights (old ones might have traces of washing powder and things).

I have my filter inlet covered in my snail tank to stop them from getting inside 

Okay so tights on the filter. And more filterations, so I gues a another 50 or 40 gallon rated filter.

Skwiishee sometimes leaves from my live plants get sucked on a filter and theyre covered in algea so Molly went to get a leave because she's a pleco and got stuck on the filter.

Also one last question. Sorry for making a rainstorm of them. How many goldfish could I put in my tank along with the commmon and lionhead already in it?

Thank you all!

Hi Fantailer,
A 55 gallon tank is a pretty long tank and with your filter being at one end of the tank, toxic gases can build up at the other end of the tank.  You should use a air pump and a diffuser or bubbler at the other end.  I run 2 filters on my 55 gallon tank. I have a Aqueon 55 on one end and then on the other I run a eheim canister filter.  I also have a diffuser which gives off fine bubbles in the middle back of the tank.
If your fish got caught on the intake tube I would bet that he/she was really weak and was ill.
I've never used the panty hose on the filter, and it will get dirty with debris so you will have to clean it off quite often I would imagine.
Also, were these fish quite new or have u had them awhile?
New fish should all be treated with antibiotic food for two weeks and also treated for parasites.
Good luck with the fish that are still alive.  Hope they stay well.

a 55-gallon with a common and a lionhead is more than fully stocked; don't add any more goldies

Mindemae, Molly was huge but she got stuck in the filter 7-8 months after I got her. But Firefly is the one I really bad about he died 2 moths after I bought him, he was huge for his age.Also one of the reasons I made this thread was because my two strongest/oldest fish who were Orbitz and Titan died about two weeks ago. Orbitz got stuck in the filter after almost recovered from dropsy. Titan got a parasite that I thought was ich.

Okay about stocking levels I'll leave at 2 or 3 goldfish. Would snails have proper space in my tank or are they like fish and need like 5 or 6 gallons each?

Midemae I will start treating them when theyre in quarintine.

Thank you all for the advice!

Fantailer.....
Here's my sponge on my filter intake.  It works like a charm.  Easy to clean and doesn't need rubber bands to hold it in place.

Thanks scrivens and sajacobs. I really need to get my tank back together.