Guide:Duke Fishron strategies

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Duke FishronFirst PhaseHardmode exclusive

Map Icon

 Classic

 Expert

 Master

Statistics

Type	BossAquatic
Environment	Ocean
AI Type	Duke Fishron AI
Damage	100/140/210 (contact) 200280420 (contact when enraged) 80100150 (Sharknado) 100150225 (Detonating Bubble)
Max Life	60000 (Desktop, Console and Mobile versions)7800099450 / 50000 (Old-gen console and 3DS versions)
Defense	50 100 (when enraged)
KB Resist	100%
Immune to

Inflicts

Inflicts

Debuff	Bleeding
Debuff tooltip	Cannot regenerate life
Chance	33%
Duration	6–20 7.5–25

Debuff	Feral Bite(Desktop, Console and Mobile versions)
Debuff tooltip	Increased damage, Decreased life regen, Causes status effects
Chance	33%
Duration	3–10

Drops

Coins	25 GC (Desktop, Console and Mobile versions) 1 GC (Old-gen console and 3DS versions)62 GC50 SC

created

created

created

• Sharknado
  
• Sharknado Bolt
  

Sounds

Hurt
Killed
Summoned
Detonating Bubble
Sharknado

• Internal NPC ID: 370
• Internal Buff ID: 30, 148
• Internal Projectile ID: 384, 385

Duke FishronSecond/Third PhaseHardmode exclusive

Map Icon

 Classic

 Expert

 Master

Statistics

Type	BossAquatic
Environment	Ocean
AI Type	Duke Fishron AI
Damage	120201302 (contact, second phase) 184 (contact, third phase) 277 (contact, third phase) 200280420 (contact when enraged) 160200300 (Cthulunado)
Max Life	30000/6000039000/7800049725/99450
Defense	40 (second phase) 0 (third phase) 100 (when enraged)
KB Resist	100%
Immune to

Inflicts

Inflicts

Debuff	Bleeding
Debuff tooltip	Cannot regenerate life
Chance	33%
Duration	6–20 7.5–25

Debuff	Feral Bite(Desktop, Console and Mobile versions)
Debuff tooltip	Increased damage, Decreased life regen, Causes status effects
Chance	33%
Duration	3–10

Drops

Coins	25 GC (Desktop, Console and Mobile versions) 1 GC (Old-gen console and 3DS versions)62 GC50 SC

• Item (Quantity)Rate
• One of the following 5 items will be dropped
• Bubble Gun
  20%
• Flairon
  20%
• Razorblade Typhoon
  20%
• Tempest Staff
  20%
• Tsunami
  20%
• Fishron Wings
  6.67%
• Greater Healing Potion (5–15)
  100% (Desktop, Console, Old-gen console and Mobile versions)
• Greater Healing Potion (5–15)
  100%
• Lesser Healing Potion (5–15)
  100%
• Duke Fishron Mask
  14.29%
• Duke Fishron Trophy
  10%
• Treasure Bag(Desktop, Console and Mobile versions)(Duke Fishron)
  100%
• Shrimpy Truffle(Desktop, Console and Mobile versions)
  100%
• Duke Fishron Mask
  14.29%
• One of the following 5 items will be dropped
• Bubble Gun
  20%
• Flairon
  20%
• Razorblade Typhoon
  20%
• Tempest Staff
  20%
• Tsunami
  20%
• Fishron Wings
  10%
• Gold Coin (25)
  100%
• Pork of the Sea(Desktop, Console and Mobile versions)
  25%
• Duke Fishron Relic(Desktop, Console and Mobile versions)
  100%

created

created

created

• Cthulunado
  
• Sharknado Bolt
  

Sounds

Hurt
Killed
Attack
Detonating Bubble

• Internal NPC ID: 370
• Internal Buff ID: 30, 148
• Internal Projectile ID: 386, 385

 "Mutant terror of the sea." 

Duke Fishron is a Hardmode Boss and one of the final Bosses in  Old-gen console and 3DS versions of Terraria.

Spawn Condition

Duke Fishron can be spawned by using a Fishing Pole with a Truffle Worm as Bait in the Ocean. Truffle worms can be found in the glowing mushroom biome.

It must then be fought within the Ocean Biome or else it will become enraged.

The Fight

Duke Fishron has two phases normally, and a third phase in Expert Mode(Desktop, Console and Mobile versions) and Master Mode(Desktop, Console and Mobile versions).

First Phase

Duke Fishron will attack in three different ways during the first phase. The first thing Fishron will do is begin his charging flurry. He will charge towards the player exactly five times, with a short pause between each charge.

After each charge, he will execute one of the two Projectile attacks:

• The first attack fires around 20 Detonating Bubbles;
• The second attack will create two small Bubbles on either side of where he is located that will each generate a Sharknado. The Sharknados are not only tall and do damage, but they also fire Sharkrons towards the player.

Second Phase

When Duke Fishron falls below 50% health, he will stay stationary for a second, then his eyes will glow as he enters his second stage. His damage and speed increase significantly. However, his defense drops to 40.

His charge flurry only has 3 charges, but they are a bit faster than before. He still has two kinds of projectile attacks, but their patterns change:

• The Detonating Bubble attack now causes him to move around in a circle, dropping the bubbles in a circle around his original location. This spreads out the bubbles, making it more difficult to pop them all. It also makes it difficult to hit Duke Fishron consistently, so this can be a good time to refill your mana with a Mana Regeneration Potion or re-apply Ichor.
• His Sharknado attack upgrades to summon a Cthulhunado. He will fire a special bubble that homes in towards the nearest player. The bubble deals no damage on contact, but it will spawn a Cthulhunado, an upgraded version of the Sharknado that is much taller, deals more damage, fires more Sharkrons, and lasts much longer.

Duke Fishron's charging attack is his primary attack and can be difficult to dodge when without proper mobility accessories.

The key to dodging it is to try to move perpendicularly to where he is aimed, right before he makes his charge. For example, if you are horizontal with him when he is about to charge, you need to quickly move up or down. (The fastest way to drop down is to briefly mount a Slimy Saddle or Gelatinous Pillion). If he is right above or below you, then you need to quickly move left or right. Do not fly all the way into the space layer, or the reduced gravity will render you helpless.

One important element of the Sharknado attack is that they will spawn in the location where Duke Fishron was when he fired the attack, and they will despawn almost exactly when he is ready to drop another pair of Sharknados.

As long as the player keeps in mind what attack Duke Fishron will do next, the player can put him in a position that makes it hard for the player to hit the Sharknados themselves. For example, during the charging flurry before the Sharknado attack, the player can move towards the edge of the screen, horizontally. That way, the player can run the other way knowing that they will not encounter Sharkrons from that direction. This also means that attacks towards Duke Fishron will also be towards the direction of incoming Sharkrons.

Also, note that Duke Fishron's first attack will always be bubbles.

Sharknados are quite tall; getting over them will require fast Wings or an infinite flight mount like the Cosmic Car Key(Desktop, Console and Mobile versions).

The upgraded Sharknado attack is a bit more difficult to deal with. It's taller, and it does more damage than the original, plus it fires more Sharkrons.

However, there is one thing that makes it a bit easier to deal with: the Cthulhunado will spawn in the location where you were when the bubble hit you. This gives you a bit more control over where the tornado spawns, so you have more of a chance (if you are fast) to make sure it doesn't spawn in an inconvenient place. You likely do not have the speed to outrun the attack, but you can help get it out of the way.

The downside of course is that, once the bubble hits you, you need to quickly move, lest it spawn on top of you. Do not allow the bubble to hit you while you are moving upwards straight or on the ground, or you are likely to take damage (and possibly get stunlocked) from it immediately.

Another important factor to note is that you should attempt to avoid a Cthulhunado by any means necessary. They deal about 100 damage, which will turn the fight in Duke Fishron's favor. Always use Wings to fly over them. Alternatively, use the Rod of Discord to teleport to the other side.

Expert Mode

Duke Fishron’s Phase 2 lunges are delayed by a second, requiring that you time your dodges a bit later than usual to avoid them.

When Duke Fishron drops below 9000 health, he will transform again and the background will notably darken, while making himself invisible except for his glowing eyes.

He will only be able to use his charge attacks in this stage, but he will gain the ability to teleport behind the player before attacking. The charges will come in a set pattern: After teleporting, he will successively charge once, then twice, and finally three times before the pattern resets.

While his contact damage is reduced, the high speed of his charges can cause you to get hit many times in a quick succession. Pay attention to his attack pattern, and make sure to not stand still during the fight. Dashing around can help avoid attacks more easily; be sure to move perpendicular to the direction that Duke Fishron will dash in. You should also try to get away from any Cthulhunados left from the second stage.

Dodging Duke Fishron's attacks in his final phase.

Because Duke Fishron is untargetable while teleporting, minions and many slower homing weapons will almost stop working entirely. As there won't be many opportunities to deal damage, you should try to deal as much burst damage as possible during his charges. Slow, highly-damaging weapons like the Sniper Rifle and Tactical Shotgun work well during this phase.

A possible strategy for this form is placing a teleporter with a pressure plate on top at surface level, and an actuated teleporter on a platform 200 blocks above, which you can use to fall endlessly, and giving Fishron a hard time hitting you.

Note that, after the battle is over, care should still be taken. If he has launched a Cthulhunado, it may still fire Sharkrons. He may also have died in the Cthulhunado, so don't charge into it to collect his drops until it dissipates.

General Strategies

General Tips

This content is transcluded from Guide:Practical tips § Combat.

• Boss battles can be won or lost before the battle ever starts. Choose your equipment and have it ready; find and/or make potions and placed buffs; use the highest-tier food you have available; set up an arena appropriate to the boss; learn the strategies for the boss you're facing.
• Prepare your Boss-fighting arena with adequate lighting, Campfires and Heart Lanterns for health regeneration, and Stars in Bottles for mana regeneration if you use magic. Bast Statues(Desktop, Console and Mobile versions) will provide a significant defensive boost. Garden Gnomes(Desktop, Console and Mobile versions) and (Desktop, Console and Mobile versions) (if underground) proper torch placement will reduce damage taken and increase damage dealt due to the luck. The Torch God's Favor(Desktop, Console and Mobile versions) helps with this. Honey pools can also be used for extra health regeneration.
• (Desktop, Console and Mobile versions) Sunflowers provide the Happy!(Desktop, Console and Mobile versions) buff to nearby players, which grants a +10% movement speed bonus and 17% reduction in enemy spawn rate.
• Always carry around a stack of the highest-tier healing potion available, as relying only on natural Health Regeneration is not a good idea. Depending on the game stage, this can include items such as Lesser Healing Potions or Honeyfins. On the  Desktop,  Console, and  Mobile versions, Restoration Potions are healing potions with a shorter cooldown.
  • Likewise carry mana potions, if you use Magic.
  • The Strange Brew(Desktop, Console and Mobile versions) is also an option, which yields very similar healing abilities to Healing Potion with added chances to trigger periods of invulnerability upon consumption.
  • On the  Old-gen console version and Nintendo 3DS version, Restoration Potions can save a slot, but will likewise trigger both cooldowns.
• It is suggested to build houses for the Dryad and the Nurse NPCs in your arena. The former casts the Dryad's Blessing(Desktop, Console and Mobile versions) buff, which increases your defense and provides you with a thorns-like effect, while the latter can heal and remove debuffs instantly, at the cost of some coins.
• Bosses are displayed on the Minimap: Follow the boss's icon to track it when you're struggling to find it. You can identify the boss icons by checking their respective wiki pages.
• Once you have freed the Mechanic in the Dungeon, you can use Wire to enhance your arena with Traps and helpful Heart and Star Statues. The former helps to damage the enemies, though be careful to set them up correctly in order not to hurt yourself during the battle. The latter will spawn heart and star pickups, respectively. Connect these devices to timers to activate them infinitely.
• In Hardmode, the Brand of the Inferno(Desktop, Console and Mobile versions) and Sergeant United Shield(Desktop, Console and Mobile versions) can be used to parry incoming contact damage.
• It may be useful to summon and kill the Eye of Cthulhu or King Slime before summoning any harder boss in order to spawn an extra one-use pool of Hearts. Note that this will prevent any Heart Statues from spawning new Hearts.
• Remember to use the Sharpening Station(Desktop, Console and Mobile versions), Ammo Box(Desktop, Console, Old-gen console and Mobile versions), Crystal Ball, Bewitching Table(Desktop, Console and Mobile versions), War Table(Desktop, Console and Mobile versions), and Slice of Cake(Desktop, Console and Mobile versions) before you go to explore or battle bosses/invasions. These will give boosts that are useful to have, with the first five being class-specific. They give Sharpened(Desktop, Console and Mobile versions), Ammo Box(Desktop, Console, Old-gen console and Mobile versions), Clairvoyance, Bewitched(Desktop, Console and Mobile versions), Strategist(Desktop, Console and Mobile versions), and Sugar Rush(Desktop, Console and Mobile versions), respectively.

Terrain Preparation

The arena must be located in the Ocean, unless you're very confident that you can beat an enraged Fishron, which is usually not recommended.

• Make an arena with 3 - 5 rows of Platforms, each about 50 tiles apart due to the height of the Cthulhunados. The arena should span at least the width of the Ocean. Asphalt Blocks can be useful to outrun Duke Fishron's attacks, but since the player cannot travel through them, they can severely limit vertical movement and thus should only be used on the bottom row.
• The arena must be very tall: the tornadoes are very tall, and require a significant amount of flight time to fly over.

Gearing up

It's highly recommended to defeat Golem first if you haven't already, as these tips will take that into account. For more information about this boss, check its own strategy guide.

By this point it's recommended to have 500 maximum health via the use of Life Fruits.

Armor

• For melee users, the best offensive set consists of the Chlorophyte Mask, Monk's Shirt(Desktop, Console and Mobile versions) or Shinobi Infiltrator's Torso(Desktop, Console and Mobile versions), and Valhalla Knight's Greaves(Desktop, Console and Mobile versions). Alternatively, Spooky Breastplate can be worn if you prefer a hybrid set. If defense is preferred, Beetle armor can be used with the Beetle Shell.
• For ranged users, the best offensive set consists of the Shroomite Mask/ Shroomite Headgear, Shroomite Breastplate, and Red Riding Leggings(Desktop, Console and Mobile versions). The Hallowed Helmet and the Adamantite Mask are viable, more accessible alternatives that boost all weapon types and provide highest damage for rocket type weapons.
  • The Red Riding Dress(Desktop, Console and Mobile versions) has slightly worse ranged bonuses, but it makes up for it with its large boost to summon damage.
  • The full Shroomite set has better damage output when stealthed, but maintaining stealth is not feasible in singleplayer mode.
• For magic users, the best offensive set consists of either Spectre armor or a hybrid set consisting of Hallowed Headgear, Spooky Breastplate, and Dark Artist's Leggings(Desktop, Console and Mobile versions). Spectre Hood can be used to heal when your health is running low.
• For summoners, the best set consists of Spooky armor. Tiki armor is a viable option that boosts whip range, which is especially important when using low range whips like Firecracker(Desktop, Console and Mobile versions). For a bit more survivability, Hallowed armor can be used.

Weapons

For Melee users:

• (Desktop, Console and Mobile versions)The Terra Blade scales with melee speed as well as damage and critical chance, and its large projectile makes hitting Duke Fishron easy.
• The Influx Waver(Desktop, Console and Mobile versions) is a very powerful choice if you have defeated Martian Madness already.
• The (Desktop, Console and Mobile versions) Christmas Tree Sword works very well against Duke Fishron, as the boss chases the player, flying directly into the trail of ornaments.
• The Seedler(Desktop, Console and Mobile versions) is an excellent option due to its auto-targeting nature.
• The Possessed Hatchet has lacking DPS, but a very reliable homing projectile.
• The Eye of Cthulhu(Desktop, Console and Mobile versions) is the best Yo-yo that can be used at this point.
• Vampire Knives are very useful for stealing life combined with decent damage.
• The Scourge of the Corruptor is somewhat low in damage, but it makes up for this by homing in on Fishron during the fight.
• The Sergeant United Shield(Desktop, Console and Mobile versions)is useful during the third phase of the fight, for those who are bold enough to try parrying the Duke's attacks.

For Ranged users:

• The Xenopopper(Desktop, Console and Mobile versions) is an extremely powerful choice when used with Crystal Bullets, but will often be unable to target Duke Fishron when he is offscreen.
• The Chain Gun, Tactical Shotgun, and Sniper Rifle are also highly effective when using Crystal Bullets. Chlorophyte Bullets are a more accurate but significantly weaker alternative.
• The Piranha Gun is good for Duke Fishron's third phase as it can latch on to teleporting enemies.
• The Aerial Bane(Desktop, Console and Mobile versions) is very useful with its extremely high DPS and splitting arrows, dealing damage to the Sharknados as well.
• Ichor Arrows, Bullets, or Darts(Desktop, Console and Mobile versions) will reduce his defense significantly, since he is vulnerable to Ichor.
• The Snowman Cannon is powerful against him, if you have defeated the Frost Moon. Electrosphere Launcher(Desktop, Console and Mobile versions) is noticeably stronger, but lacks homing abilities.
• (Desktop, Console and Mobile versions) The Elf Melter has consistent, high damage and a wide hitbox, and the boss tends to stay within its range as it chases you. The Flamethrower is a weaker alternative.
• The Chlorophyte Shotbow with Ichor or Holy Arrows can perform excellently against him.
• The Stynger is very effective.
• The Megashark and Onyx Blaster(Desktop, Console and Mobile versions) are weaker, but they are available much earlier in progression.
• The Daedalus Stormbow(Desktop, Console and Mobile versions) with Ichor Arrows is the best ranged option for dispatching Duke before defeating any other Hardmode boss.

For Magic users:

• The Razorpine is very strong due to its excellent DPS, although it requires you to get closer than with other weapons.
• The Nightglow(Desktop, Console and Mobile versions) is also very strong because of its homing ability and high DPS.
• The Golden Shower spell is helpful as it reduces his defense and easily pops all the Detonating Bubbles.
• Betsy's Wrath(Desktop, Console and Mobile versions) is a higher DPS alternative to the Golden Shower that also lowers his defense more, at the cost of having to get a bit closer.
• The Spectre Staff is effective due to its homing nature allowing one to focus on dodging, especially during the third and final phase in Expert/Master Mode.
• The Inferno Fork clears out bubbles easily and deals moderate amounts of damage.
• The Blizzard Staff is very good for attacking while he is stationary.
• The Laser Machinegun(Desktop, Console and Mobile versions) can be used if the player has already defeated Martian Madness.
• The Magnet Sphere can deal a lot of damage and only needs to be cast once in a while.
• The Heat Ray is also a viable option.
• The Spirit Flame(Desktop, Console and Mobile versions),Crystal Serpent(Desktop, Console and Mobile versions), Rainbow Rod, and Venom Staff(Desktop, Console, Old-gen console and Mobile versions) are the best pre-Plantera magic weapons against this boss, with the former two being available at the start of Hardmode.

For Summoners:

• The Terraprisma(Desktop, Console and Mobile versions) is the best minion available. Pair it with the Kaleidoscope(Desktop, Console and Mobile versions) for the maximum damage output possible.
• (Desktop, Console and Mobile versions) The Xeno Staff(Desktop, Console and Mobile versions) is a consistent and powerful minion. It should be used with a combination of Dark Harvest(Desktop, Console and Mobile versions) and Morning Star(Desktop, Console and Mobile versions) (or Kaleidoscope(Desktop, Console and Mobile versions) if available) for stacking tag damage.
• The Blade Staff(Desktop, Console and Mobile versions) is also reliable and tends to completely nullify Fishron's bubbles, but depends heavily on tag damage from whips. It should be used with Dark Harvest(Desktop, Console and Mobile versions) and Morning Star(Desktop, Console and Mobile versions) (or Kaleidoscope(Desktop, Console and Mobile versions) if available), and alternating between the two to stack tag damage is highly recommended.
• (Desktop, Console and Mobile versions) The Desert Tiger Staff(Desktop, Console and Mobile versions) is a powerful alternative. It should be used with Firecracker(Desktop, Console and Mobile versions), though you should be mindful of its slightly shorter range.
• The Sanguine Staff(Desktop, Console and Mobile versions) is the best option available upon reaching hardmode. It is obtained as a drop from the Dreadnautilus. Pair it with Durendal(Desktop, Console and Mobile versions) and/or Firecracker(Desktop, Console and Mobile versions) if available.
• The Sergeant United Shield(Desktop, Console and Mobile versions), although not a summon weapon, is a useful side-weapon due to its armor-increasing and parry abilities, and its ability to inflict flask debuffs from a long distance.

Accessories

• Quick aerial movement is a must-have for the fight. The most natural option is to use Wings, though without boosts, most wings do not have enough vertical speed to consistently dodge the Duke. Frog Leg can make them significantly faster, making it easier to get over the Cthulhunados and dodging his attacks while flying.
  • Alternatively, one can obtain the Jetpack. The high vertical speed makes it an ideal choice for dodging Duke Fishron without the need of the Frog Leg, though having the Frog Leg can make it even more effective at dodging Cthulhunados. (Desktop, Console and Mobile versions) Desktop users can also use the Empress Wings(Desktop, Console and Mobile versions).
  • The Amphibian Boots(Desktop, Console and Mobile versions) allow for increased ascent speed with wings and fast running, even on normal tiles. On  Old-gen console and 3DS, Lightning Boots or Frostspark Boots can still give the increased movement speed.
• The Master Ninja Gear and Shield of Cthulhu(Desktop, Console and Mobile versions) provide a dash, which is invaluable for mobility.
• Accessories that increase damage are a must have for ending the battle sooner. The best choices include the Celestial Shell(Desktop, Console and Mobile versions) or Stone, Destroyer Emblem, Mechanical Glove, and Sniper Scope.
• Cross Necklace or Star Veil can prevent heavy damage from getting trapped inside a Sharknado or a big group of homing bubbles.
• Due to the boss' high damage, the Magic Cuffs or Celestial Cuffs(Desktop, Console, Old-gen console and Mobile versions) can almost completely restore the player's Mana from one hit.
• If you are using The Eye of Cthulhu(Desktop, Console and Mobile versions) or another yoyo, use a Yoyo Bag(Desktop, Console and Mobile versions).
• Charm of Myths will both allow for increased regen and reduced time for the Potion Sickness debuff. The Philosopher's Stone effect can be used without the need of investing an accessory slot by keeping it on a vanity slot until needing to heal.
• The Cosmic Car Key(Desktop, Console and Mobile versions) mount is a good replacement for Wings. While its movement is generally slower and less versatile due to being unaffected by other mobility accessories, it can save the slots for other defense or damage improvements.
• Expert Mode players who have encountered the Pumpkin Moon are recommended to use the Witch's Broom(Desktop, Console and Mobile versions), as it has a fast overall speed and is able to travel in water.
• An Ankh Shield will protect from the Bleeding debuff and those caused by Feral Bite(Desktop, Console and Mobile versions), and will also provide knockback resistance.
• The Superheated Blood(Desktop, Console and Mobile versions) mount can be used in this fight due to its high mobility through water without having to use asphalt blocks.
• Gelatinous Pillion(Desktop, Console and Mobile versions) and Slimy Saddle(Desktop, Console, Old-gen console and Mobile versions) can help you to move fast vertically, which is extremely useful during the 3rd phase.

Potions and Buffs

• Inferno Potion is highly recommended as it will destroy the Detonating Bubbles Fishron spawns before they reach the player.
• Regeneration Potion and Ironskin Potion, Endurance and Lifeforce will improve survivability.
• Any food item that can provide the Well Fed buff or better is very welcome.
• Swiftness Potion can help you evade Duke Fishron's attacks.
• Wrath Potion and/or Rage Potions for a boost in damage output.
• Magic Power Potion and Mana Regeneration potions are a must for Magic users.
• Water Walking Potions can be used as a substitute for a platform in the Ocean.
• Gravitation Potions can free up an accessory slot. It is recommended to use Featherfall Potions with them.
• Melee characters should use the Tipsy debuff and the Flask of Ichor if available.
• If you are facing him at night, a Shine Potion, Night Owl Potion, and Hunter Potion will improve visibility.
• Summoning Potion increases the damage output for the summoner class.

More In-Depth Strategies

Minecart Strategy

This strategy differs from others in that it doesn't use a skybridge, replacing it with looped minecart track above the ocean, so the player won't have to deal with his enraged behavior. It does, however, need some more work than other ones, especially when building the arena.

an example of a Duke Fishron Minecart Strategy

Materials

• 600-1200 normal minecart tracks for building loop + 2 booster tracks
• Any kind of hammer

Arena Preparation

The essence is to make looped minecart track approx. 60 tiles above Ocean itself. It should consist of at least 600 tiles; while shape is pretty loose, it should have at least two places in which player drastically changes altitude, as well as at least 100 tiles long flats.

One should also make a "Starter" - a short molo with boosters, from which player will summon Duke Fishron and quickly escape to the loop.

It should be noted also that arena shouldn't exceed Ocean biome.

Execution

When everything's done, player should sit in a minecart on "Starter" and summon the Fishron. As soon as it's done, one should quickly go to loop (boosters will help). At this point, everything that remains is to shoot Fishron while maintaining speed on track, healing a/o replenishing mana when needed. Some tips:

• Use a homing weapon, especially if your arena is pretty large. Fishron will spend most time off-screen, and high speed will often change directions you're facing.
• Though stock minecart shouldn't be used, Mechanical Cart is not a good choice. Even though with it provides defense bonus, as well as speed to avoid Fishron's charges, it can easily outrun him causing Fishron to despawn, which is possible on larger arenas. Higher speed means also that you will more often run into Sharknados.
• Try to make arena consisting of approx. 800 tiles, but don't make it horizontally-long. If you do so, Fishron will frequently run into you, and Cthulunados in his second stage will quickly kill you as there won't be any way to dodge them.

Abuse of Invincibility Frames

(3DS version) Standing on a Spike with a Cross Necklace equipped will give the player invincibility frames for almost all of the fight while taking extremely little damage from the Spike itself.

Enraged Anti-Gravity Hook Strategy

On  Old-gen console and 3DS versions, When enraged, Duke Fishron is much faster and does much more damage. But with this strategy, this strength can be turned into a weakness. What you must do is get an Anti-Gravity Hook and place one or more platforms in the air. After Duke Fishron becomes enraged, you use your Anti-Gravity Hook in the platform and start using it to spin in a circle. This makes it possible to dodge all attacks. Keep in mind that this strategy only works with enraged Duke Fishron, because in his enraged behavior he will do nothing but attempt to ram you. Then you use the hook on the platform, start spinning and dodge his charges.