G'day swimming fish
Where to start.
OK BN first. Bristlenose catfish are vegetarians. Calling them algea eaters is a bit of a misnomer. Younger BN's will eat algea off the glass, but older ones prefer proper food.
Algea wafers should really only be a suppliment to a vegetarian catfishes diet. Good vegies for your BN will be zuccini, cucumber and romain lettuce, some may also like sweet potatoe, but usually panaque catfish like the harder veggies. I usually alternate veggies one night, algea wafer the next.
All you need to do is cut a zuccini length ways down the middle and cut about an inch for it and glad wrap the rest and put in the fridge. You'll soon learn how much it'll eat in one night. In our house we eat a lot of fresh veggies, so it's just a matter of seeing what's on the nights menu. So far I have found my catfish will eat broccoli and asparagus stems, peas in the pod and beans, as well as what I mentioned above. Just give the vegies a real good wash. Lots of these vegies float, so I just rubberband a piece to a small rock in the tank.
Becuase catfish eat a lot of vegies, they produce a lot of waste, and therefore nitrates can build up fast in a tank. I would suggest you look at doing a 30% to 40% water change every 3rd day in a 10 gallon tank.
So the GT. Have you read the profile
here at C-F? I don't know how fast a GT grows, but I would guess it should reach about 6 inches in length in 6 months if fed properly. So I think your GT will out grow your 20 gallon tank in less than 6 months.
It's my opinion that a 55 gallon tank will not be large enough for an adult male GT. This thread
might be a suitable read to give you an idea of what size tank may be appropriate for an adult GT. Like I said, it's my opinion, and each of us here has differing views on what constitutes a suitable sized tank for certain fish.
It would be good for GT keepers here at C-F to offer some advice, even if it's to say my advice is wrong. [/url]