We are limited to a 55 gallon tank due to living in an apartment, space etc. etc. etc. I know that you are only supposed to have 1 fish per gallon of water. Does that include like fresh water crabs and such? Because my daughter likes the cichlids and tetras, and me and the fiance like the crabs and sucker fish. Would these fish do well with each other and is my thinking on the tank right?
A 55G is a nice size tank that gives you lots of stocking options. However, if you have not bought the tank yet, have a serious look into 75G tanks as well. Both are 4' long tanks, and a 75G takes up hardly more floor space. Also, the price difference is often small, especially when buying used, but a 75G opens up even more stocking options due to the extra width.
The "rule" is 1 inch of fish per gallon of water, but that rule is total nonsense. Anybody who pictures a 10" oscar in a 10G tank will see that immediately - the fish would hardly be able to turn!
When stocking fish, and especially cichlids, you need to consider where in the tank those fish will live. If you choose all fish that claim areas at the bottom of the tank, then you will be restricted to far fewer fish than if you choose some that prefer to sit at the bottom, some that are in the middle (for example in the caves of a large rock pile), and some that stay mostly at the top.
In addition you need to consider dietary requirements, required water parameters, and temperament of the fish when deciding what can be mixed in a tank and what not. A lot of crabs eat fish - especially smaller fish like tetras. A lot of cichlids eat crabs - especially when they shed their exoskeleton. A lot of cichlids also eat smaller fish like tetras. However by choosing the right type of cichlid, tetra and crab, you might be able to make a setup work. It just needs a lot more research :thumb: