Yeah washing the cucumber is important particually if its not organic, it will have small amounts of pesticides and herbicides on it which is not good for fish (or us for that matter). Some people put wax on vegetables and fruits to make them appear more shiny or fresh (this is particually true for fruits like apples, that shine isn't natural
), which should also be washed off if you can.
Because cucumbers are often rather large and take while for plecs to eat, try and get as fresh a cucumber as posible so it last longer- if the cucumber is very bendy that means it is not that fresh.
Some people "blanch" their veg which means they put it in boiling water for about 20 second and then they cool it down in the fridge in some cold water to cool down- you can also microwave the cucumber slice for a couple of seconds which also has teh same effect.
Blanching just makes the cucumber easier to eat, although for most plecs it isn't nesarsary- i just feed my pleco's (1 sailin, 2 commons, 1 para plec and 1 clown plec) fresh washed cucumber slices. Blanching is more important for snails which find it harder to eat into the hard cucumber flesh.
Most plecs will leave the cucumber skin alone, you should always remove the cucumber after a day or two or whenever the plecs stop eating it to help prevent it rotting in the aquarium
.
