On Jan 29, 12:52?pm, "Pablo" wrote:
I have a small 1.6 gallon fish tank. I added a small gold fish and a
pleco. I think the tank is going through the set-up cycle (amonia
nitrite nitrate). I think the gold fish is passing out. Anyways, Is
it possible to have that small tank with no mechanical filter, just
the air stone and the undergravel filter?

Oh my! = O

From your situation, the size of the tank and the fish you've put in
it and the obvious question you're asking, I'm going to assume you
haven't researched much about fish tanks, their set ups and what is
appropriate to house the fish choices you've made.
Here's the bad news.
You have a 1.6 gallon tank. About the only thing you can house in such
a small tank is one male Betta, or a couple of the smaller viarieties
of Killifish. That's about it.
As for a Goldfish...never. Doesn't matter what type, they can't live
in a 1.6 gallon tank (unless they're a tiny baby of about a 1/4" in
long or less). Plecos....never. Again, doesn't matter which type
(there are SO many). The most commonly sold are the common Pleco's and
they grow about a foot and half in legnth. Goldfish...Commons..12" or
longer, Comets 16" long, Fancies...8" long, Koi...about 3 feet and
have no place in a tank anyway.
Now..add their huge body mass to that legnth and you end up with a
very large fish. These fish put out more waste than the average fish
of that size too, they need better filtration than normal.
An undergravel filter isn't enough and most likely your fish is
suffering from ammonia poisoning.
The Pleco will be next, and if you don't get a much larger tank very
quickly, both are going to die.
Depending on the type of Goldie it is, the fancies need about 15g per
goldfish, and the larger ones (Commons and Comets) about 20g's per
fish. The common plecos should be in a tank of about 90+ gallons when
fully grown.
Looking at my 75g, I wouldn't want to house a half grown common Pleco
in there, let along a 1.6g tank.
The best advice I can give you is to please research setting up a
tank, what's involved, then go to the species of fish.
Think of fish you like, research them.See what their requirements are
and if they are compatible with what you have, or with other fish you
may want to house with it.
This is of course if you get a larger tank.
Basically, Goldies can only with other Goldies.
Warm water tropicals need different tank requirements than Goldfish
do, so they aren't fine to keep together.
Another good piece of advice, many shop employees don't know squat,
yet act like they do.
It's much better to research on your own and if you need something
answered or a specific Q about a certain fish, etc...post it here.
In close to 30 yrs of being in this hobby I have heard so much crap
being told to customers, that's it's not even funny anymore.
Good luck, but do know that you cannot leave these fish in this tank.
They will die from it if you do.