Putting it all together

In[21]:=
  system =
    Show[
      Translate[Scale[seaweed, 1.9], {.25,.5,.2}],
      Translate[Scale[plant, 1.7], {.25,3.5,.2}],
      Translate[Scale[spider, {.5,.5,1.5}], {.5,1,.2}],
      Translate[Scale[walls, .5], {.2,2.5,.2}],
      Translate[Scale[rightroof, .5], {.2,2.5,.2}],
      Translate[Scale[leftroof, .5], {.2,2.5,.2}],
      Translate[
        Rotate[
          Scale[
            {fishtop,fishbottom,leftstripe,rightstripe,eyes},.3
          ],
        Pi/2, {0,0,1}],
      {.5,1.5,1}],
      Translate[
        Scale[
          {fishtop,fishbottom,leftstripe,rightstripe,eyes},.1
        ],
      {.3,2.75,.45}],
      aquarium,
      gravel,
      stand,
      PlotRange->{{-.5,1.5},{-.5,4.5},{-3,2}}
    ];

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