Goldfish Help

[fishman12345]

Hello everyone I wasn't sure where to put this topic, 
 
I have 4 goldfishes and a sucker fish in a 30 gallon tank with a lucky bamboo plant on the top growing nicely. THey are about 4 inches each and one of them is 2 inches. Today I saw the smallest goldfish stuck inside my filter sponge and the other goldfish were tying to tug it out. Amazingly it survived because its immortal. It has survived the jaws of my cat, the abuse from my niece, outside the water for an hour and still flopping. Literally this fish is superman. But the issue is that its eye has become really huge, it was swimming weird but now its swimming fine but I can make out something is wrong with it, I was wondering, I know this sounds cruel, should I euthanize it? I.e feed it to my cat. It scales are missing, its body is kinda bruised and now its eye has a problem. I am not sure if its in "pain" but its not well. 
 
2nd I am trying very hard to grow algae in the tank but Its not growing at all. I have tried LED lights, I have tried Black light, I have tried yellow light, sunlight directly on the tank but no growth at all. The tank is cycled 
Ammonia - 0 
Nitrite - 0 
Nitrates- 160-200
Ph- 7.2
 
3rd I want to change the water but the last time I did that my goldfish started swimming weirdly so I am scared the change will kill them. The filter sponge is filthy so all the bacteria will be in it right? and if I throw it in new water the tank should get cycled right? I ve read lot of contradictory stuff that says you shouldn't change leave the water exactly the way it is etc etc. 
 

 

[Ninjouzata]

What kind of goldfish are these? Fancy goldfish (oranda, ranchu, moors, ryukin, etc) need 30g for the first, and then 15g for each additional fancy goldfish. Comets need 75g+.
What kind of sucker fish? Do you mean a pleco? There are tons of different plecs and ones that are often sold are common plecs, which get much too big for your tank.
 
Sounds like he/she's had quite a time! I'm not sure if you should euthanize it or not, especially since it seems to be such a fighter

Hopefully someone more experienced with things like this will come along, but something that almost always helps is giving them clean water.
 
Not sure on the growing algae part.
 
How often do you do water changes? Do you use a dechlorinator when doing them? Do you temperature match?
Your nitrates are VERY high, I'm not sure at what level they become toxic but I know most people don't want to see it get over 80. This is one of the reasons why we do weekly water changes, to keep the nitrates down.
 
The filter media is what contains the bacteria, yes, but you can gently rinse it in dechlorinated water, or tank water that you have siphoned out. The tank water does not contain bacteria.

 

[214jay]

 
It scales are missing, its body is kinda bruised and now its eye has a problem. I am not sure if its in "pain" but its not well.

 

I would say it is most certainly in pain!!!
 

 
Nitrates- 160-200

I'm amazed you are not over-run with algae.  What is your maintenance schedule on this tank?

 

[Sophie]

Fresh clean water will be key to the fishes recovery.
I'd recommend doing at least an 80% water change to get those Nitrates down.
Put some of the old tank water in a bucket, take the sponges from the filter and rinse them off in the water then put back in the filter.
Continue to do smaller water changes every few days.
 
Fish with injuries and open wounds etc will not heal well, if at all in dirty water.
It's like having a cut and basically rubbing dirt/poop in it.
Especially Goldfish, they're very messy.
'Suckerfish' too are mass poop producers.
 
I'd also like to suggest treating with Waterlife Myxazin to help prevent/treat any bacterial infections.

 

[fluttermoth]

I very rarely disagree with you, Sophie, but I'm going to in this case (sorry!)
 
OP; there's every chance that your tank is suffering what we call 'old tank syndrome'. With nitrates that high, it's obvious that your tank hasn't been getting the necessary water changes, so the tank water is going to be very different from your tap water.
 
Your fish will have become acclimatised to the old water, because it's built up gradually, and too much new water could shock the fish; that's almost certainly why your fish started acting 'weirdly' last time you did a water change.
 
You will need to start off with smaller water changes and build up to larger ones. I would do 20% now and increase that by 10% a day; so 20% today, 30% tomorrow, 40% the day after that, until your tank nitrites are the same as what's in the tap water.
 
Clean your filter media gently in some old tank water. Just squeeze them to get the worst of the 'gunk' off them and no more. If you clean them in tap water, or try and scrub them, or get them completely clean, even in old tank water, you will lose most of your good bacteria.

 

[Sophie]

I very rarely disagree with you, Sophie, but I'm going to in this case (sorry!)

Please don't apologise - you have far more experience than I. I was just going by the high nitrate levels as lack of water changes therefore needing more clean water to help with recovery, I didn't think of OTS at all and how it'd affect them just how to help heal wounds.
A more enlightened contribution is much appreciated especially with my baby brain aha I can't remember what I had for breakfast
As Flutter said - little and often is now the way forward!