If it is how you described it and there are not very many organelles on the inside, then I think it is a algae cell.
<span>Cortex</span>
<span>Lymph node can be described as kidney shaped
organ of the lymphatic system and of adaptive immune system that can be found
throughout the body. The major site of lymph nodes is B and T lymphocytes and
other white blood cells. However, lymph
node associates with follicular dendritic cell in the B cell follicle and
fibroblastic reticular cell in the T cells cortex.</span>
When you do that the fish will die. That is because it will take too much water in it and die from it, or rather, the fish's cells will take too much water in.
I think he's prokaryote because of the appendages and non circular, but more oval-ish? I might be wrong