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[elephantnose3334]

Black knifefish (and serpae tetra for comparison, pen)

Marbled hatchetfish (watercolour, India ink and pen)

 

[MattW3344]

Looks great! Have you thought about attempting to make a hand-drawn and painted species poster? I know that would take a very long time but I think that would look amazing and it gives you something to work towards in both your art and fish-keeping hobby

There is a person in Japan who sells posters and pencil drawings - https://osakanacraft.thebase.in/categories/5087340

Rainbow fish example