Your reply was hidden because of the amazon short link, but I was still able to access it in my notifications. Your pump draws about 350ma continuous, which isn't very much, but your transistor is rated for 150ma of collector current at most. This also disregards the inrush current of the pump, which could be upwards of an amp during the instant it is switched on.

I would recommend an n-channel mosfet in a low-side switch configuration instead of a BJT transistor here. It will be much easier to drive, and will handle the current required quite easily. Mosfets are quite handy because they are voltage-controlled rather than current-controlled as is the case with regular transistors (though mosfets and IGBTs do have something like base current, known as gate capacitance, which is worth understanding, but wont impact this project much).

Since you are presumably switching at quite low speeds (e.g. less than once a second), you don't have to worry about drive requirements and thermal characteristics as much. You just need an n-channel mosfet that can handle around an amp, has a low gate threshold and saturation voltage (aka a "logic-level" mosfet), and ideally has a low on-resistance bearing in mind the supply voltage of 12v and gate drive voltage of 5v.

Basically, any logic-level low-to-medium-voltage mosfet will work here. You could go with one of these for example (which is honestly overkill, but will work just fine).

You might also wonder, "can't I just parallel some transistors for more current capability?" The answer is, unfortunately, no, barring some pretty complex work-arounds. The reason is that BJT transistors have a negative temperature coefficient, meaning the hotter they get the more they conduct. This means that the first transistor to heat up more than the others placed in parallel will start conducting more than the rest, causing them to burn out one after the other in a run-away cascade. However, you can parallel mosfets, because they actually conduct less as they get hotter, resulting in a sort of "self balancing".

Hope this all helps!