@ ch4rlie
how do you know that the 0 on the OP's keyboard is working? you seem to have stated that as fact.
you can also get cold water algae eaters, they used to be known as sucking loaches. they came in along the same lines as the zebra danios, originally thought tropical only but were found to do just aswell in colder temps.
i wholeheartedly agree with the advice given by fluttermoth and would go so far as to say they may in fact need more. i have one of my goldies at almost 6" (depending on whether you take the tail into account) and i would cringe to think of keeping him in my 35imp/42us g long term as altho the gallonage is enough to support his bio-load he would not have much room for movement. these fish need a lot of room to move and are actually quite active if kept in a decent sized tank.
from the calculator on here a 5" cube registers 1us g altho not an imp g, take those measurements up to 8"x7"x7" and it goes to 2us g altho still only 1imp g. as the OP is from the states i assume they are working in us g. to put 2 goldfish and three rocks in a tank this size will hardly leave room for water let alone a filter and room for the fish to move.