Preparing to get yelled at... :(

[7Enigma]

I think your best option at this point is to attempt a trade. You need to research some smaller goldfish species that look similar to koi that you can replace your current fish with. While still too small of a tank even for 4-5 goldfish, its MUCH better then the condition now. You can replace the common pleco with a bristlenose pleco (BN pleco). That will at least allow you to maintain somewhat OK conditions with FREQUENT, LARGE PWC's.

Don't give up, just change your angle. I think another way would be to get a test kit and ask your dad to check the levels. Show him what is dangerous to the fish and say, "sure you can keep the fish, just keep the levels in check". I'd be willing to bet within a week of daily PWC's he would give you the OK to replace them.

 

[Shelby_Tempo_GT]

Yeah... it's not a winter tank... Just a tank.

There is actually literally no algea in it. :?

I don't think the algae could survive all of that ammonia

 

[squeekness]

The filter you describe sounds like an Aquaclear or something similar. This is band aid on a major bleed but, most filters of that type offer cartridges or inserts with white chips in them that can help absorb some of the ammonia at least. You could try looking into adding that to your current media.

Like you, I am in a situation where my fish have outgrown my tank. Until I can find another home for them I do two major water changes a week to keep my nitrates down. I have a python to assist me and it makes my water changes a snap. I strongly suggest you purchase one also along with the water testing kit suggested above. The easier the water change is, the more likely you or your dad will do it regularly and help keep these poor fish going.

The thing is, unlike mine, your fish don't seem that big --yet. You can't just take them back, give them up for free? Most dealers will take a fish for free.