This card is one of my favourite cards in duel masters. Its special ability consists in being able to return a creature to its owners hand from the battle zone. The low mana and ability of the card make it a potential game changer if utilised effectively.
This card is most effect against high power-high mana creatures.On summoning Unicorn Fish to the battle zone, you have the option to return any one creature to its owners hand,regardless of the power of the creature.It is thus most effective when used in the later part of the game when the larger creatures start coming into play.However it also works well in a rush deck as it helps create a numerical advantage of your creatures compared to your opponents creatures.Its effectiveness against psychic creatures is even more immense as it allows you to return a psychic creature back to your opponents hyperspatial zone(psychic creatures do not go to hand).
Strategies and game play:
The key is to use this creature at the right point during the match.If you play with a rush deck,you can summon it with any low power speed attacker,say pyrofighter magnus,rikabu the dismantler etc.This creates a huge numerical advantage in your favour as you now have +2 creatures in the battle zone while your opponent is -1.If you summon this at the later stage of the game,it can be used to return one of your opponents most powerful creatures to his hand.The added advatage of this is not only that one of your opponents turns go waste,for if it is a very important creature the opponent is likely to summon it in the next turn again, but also that you now roughly know what your opponent will do in his next turn and can thus plan your game accordingly.Moreover it is different from spiral gate(aside from the fact that it is a creature) in that you may even choose one of your own creatures and return it to your hand.Thus for example if you are sure that one of your creatures is going to get destroyed next turn, you may return it to your hand,thus saving it from being sent to your graveyard.
Combos with other cards:
A great combination is if you combine Unicorn fish with speed attackers like rikabu or bravehart dragon.The combined mana is just 7 and has a huge element of surprise!This combination is also very effective in finishing of the game by bringing a speed attacker to the battle zone while at the same time removing a potential blocker from the battle zone.Another good combination is to combine it with Spiral Gate,thus totally disturbing your opponents game plan and giving you a huge advantage by sending back two of his creatures.Again the combined mana is just 6.If used with Aqua Sonicwave at an earlier stage of the game,it can also return two of your opponents creatures while adding two of your own creatures thus bringing the numerical advatage to +2 ,-2.And again the mana is fairly low at 7.If your opponent is overly defensive in his approach you can combine it with Comit Missile to destroy one of your opponents blockers and return one to his hand,the mana for both combined being just 5.Even creatures who are immune to water spells can be returned to their owners hand through the use of unicorn fish.You can also return one of your own creatures which on being summoned use their ability to your own advantage,like Bronze-Arm Tribe,Aqua Hulcus,Locomotiver,Gajirabute, Vile Centurion etc.
Ways to counteract it:
This card is not effective sgainst creatures which say,when your opponent chooses a creature in the battle zone,this creature cannot be chosen.Again using Unicorn fish to send your opponents speed attacker to his hand actually has a counter effect as not only can it not be attacked this turn(as it is not in the battle zone) but also that it will have the still have the effect which its owner intended on the game(being a speed attacker).
Its primary strenght consists in disrupting the game plan and strategy of your opponent by returning one of his creatures and adding one of yours.This is a major disruption as the returned creature on being summoned again,again suffers from summoning sickness(unless it is a speed attacker or evolution creature),and thus its impact on the game is delayed,rendering it at times worthless.
Its main weakness is its low power.Even though its most important impact on the game is independent of its power,yet after that it is left as a weak creature in the battle zone and can thus easily be destroyed.
Apart from the English edition of the card in the base set,it is also in Japanese in Deck Builder DX: Alien Edition,the artwork however being the same for both.
Artwork and aesthetics:
The tentacles at the side of Unicorn Fish seem to be a clear indication of its ability to pick up something and drop it someplace else(i.e.from battle zone to hand).The small description given after its ability is also very apt, as it indicates that the ability of this creature holds good for all creatures alike,allies and foes(as you can even choose one of your own creatures to return to hand.
For its effect on entering the battle zone,low mana and element of surprise,i give Unicorn Fish a 9/10.