How to create a PHP rule with if statement and push an certain array?

How can I create a PHP if rule(s) and push a certain php array:

Let's say I have 3 numerical values that come from POST:

$Tanks= intval($_POST["Tanks"]);
$Fish= intval($_POST["Fish"]);
$Vegetables= intval($_POST["Vegetables"]);

The request is:

Request: Tanks -> 2; Fish -> 4; Vegetables ->1

And I want to create PHP IF rule(s) if the above results are met to push the below array(s):

array_push($tank,array("objType" => "Fish"), array("objType" => "Fish"));
array_push($tank,array("objType" => "Fish"), array("objType" => "Fish"), array("objType" => "Vegetables"));

I have spent several days with this matter and hope that the new year to bring me the answer.