i have 1 goldfish atm in a tank (approx 45 litres) it has an internal filter. how do i stop the algae from appearing or slow it down? is there a coldwater fish that goes with fantails that eat algae?
I wouldn't advise putting any algae eating fish in with the goldfish as its a risky game- a lot of algae eating fish (like pleco's) can grow quite territorial while others aren't really suited to the same habitat as goldfish. If you are getting incessant algae problems i would advise checking the nitrate levels of the water (high levels of nitrates will lead to algae problems) as well as the lighting (if its very strong it will also cause algae problems).
My sister has a chinese algae sucker thing and its living fine with her goldfish, not all do but look into it, some algae eaters (sucker fish) will tolerate lower water temps