So after months I have decided to get my 3 gallon tank up and running again. I have the following 2 questions and need all the advice I can get to ensure I have a nice happy tank
Q1 Are the following options possible to house in a 3 gallon tank, and which would be the best option?
A) a pair of goldfish
B) a single pair of bettas with shrimps
C) a couple of guppies with shrimps
D) Maybe a pair of mollies/plattys with some shrimp?
Q2 Are there any other types of fish I can house in the tank besides those mentioned above?
All kinds of advice and suggestions on a 3 gallon tank ( this is the only tank size I can keep in my room) will be greatly appreciated
Q1
A) Goldfish get massive. They are kept in bowls as you pointed out but this is because of generations (possibly centuries) of ignorance and misconceptions. Goldfish get big, really big, and keeping them in small tanks is nothing short of animal abuse. So no, goldfish will not be suitable unless you can give them 30 gallons or more. I have mine in 60 gallons which is more than absolutely necessary but with a potential to reach over 10 inches (over 18 inches in the case of commons) it's not really fair to skimp on the space.
B) A pair of bettas? Noooo. Quite aside from the fact the male betta splendens should be kept alone and that also includes females, 3 gallons wouldn't be big enough even if they were friendly enough to keep together. A single betta - maybe. Most people will be happy to see a single betta in a 3 gallon, although I'd give it more room if you can.
C) Some guppies and shrimp is much more like it. Don't keep mixed sex or female guppies as with a 3 gallon tank you have zero spare room for breeding (and females can come from the shop pregnant). I think a trio of males would be OK, with 5-10 small shrimp. Some might feel this was over stocked though.
D) Mollies will get far too big. I wouldn't recommend less than 15 gallons for a regular molly and 20 gallons for a sailfin. At 4 inches a molly will be very miserable in there. Platies are still not suitable, despite being smaller. 3 gallons is a very tiny tank and only suitable for very tiny fish, with a single betta being a possible exception to that (I still aim for 5 gallons per betta).
Q2
Not many. If it is a rectangular tank and of traditional 'tank' shape (i.e. longer than it is tall) you might be able to get away with a trio of sparkling gouramis or 6 chilli rasboras. Anything you pick has to be very tiny (well under an inch). Could maybe get three male endlers instead of guppies. I think they stay smaller. My personal preference for such a small tank is to keep it as a planted shrimp tank.
Q3 (a Q of my own)
How are you planning to cycle it? You are going to cycle, right?