Appearance-wise, they are fish (or water-based organisms) controlling robotic suits from inside water-filled bowls. The word is a portemeneau of words "fish" and "cyborg".
Due to their lack of support and consistency, "Fishborg" monsters are generally used as engines for WATER-oriented Decks, mainly those ones capable of performing Synchro Summons. All of them have the ability of Special Summoning themselves from the Graveyard if a certain condition is met or if a cost is paid. In the case of "Fishborg Blaster", that cost is a WATER monster discard, which in turn, if combined with "Atlantean"/"Mermail" monsters or "Superancient Deepsea King Coelacanth" could provide huge card advantage and enable powerful OTKs. Also, due to the fact it can indefinetely revive itself as long as that cost is paid, it has been Forbidden since 2011. All "Fishborg" monsters are watered down versions of "Blaster", but, with the proper set-up, they can effectively be used to set-up the Synchro Summon of powerful monsters, such as "Trishula, Dragon of the Ice Barrier", "White Aura Whale", etc.