Short answer

Yellow tang (most peaceful, vibrant, tolerates community), kole tang (small, peaceful, exceptional algae grazer), tomini tang (shy but peaceful), or sailfin tang (large but peaceful). Avoid achilles, powder blue, and clown tang in 100 gallons - they need 180+ gallons.

In depth

Tangs (Acanthuridae family) are reef-tank centerpieces but demand swimming space. The 100-gallon mark is roughly the floor for keeping one tang long-term; 125-180 gallons is better for most species; 220+ gallons is required for the demanding ones.

100-gallon tang selection

  • Yellow tang (Zebrasoma flavescens): the standard hobby tang. 5-6" adult, peaceful with most reef inhabitants, exceptional macro-algae grazer, $80-180.
  • Kole tang / Yellow-eye Kole (Ctenochaetus strigosus): 4" adult, the best algae cleanup of any tang, peaceful, $80-150.
  • Tomini tang (Ctenochaetus tominiensis): 4-5" adult, peaceful, similar to kole but slightly smaller adult size, $80-150.
  • Sailfin tang (Zebrasoma desjardinii or veliferum): 8-10" adult, peaceful but large - 100 gallons is the floor for one, 125+ ideal, $120-250.

Avoid in 100 gallons

  • Achilles tang - 180+ gallons, ich-magnet, advanced-only
  • Powder blue tang - 180+ gallons, ich-magnet
  • Naso tang - 220+ gallons, large adult size
  • Clown tang - 220+ gallons, aggressive
  • Two same-species tangs in 100 gallons - even peaceful species fight when confined

More questions

Can I keep two tangs in a 100-gallon?

Generally no. Even peaceful species fight in 100 gallons. The exception: 2 small Ctenochaetus (kole + tomini) sometimes coexist if added simultaneously as juveniles. Plan for fights and remove the loser if needed.

Do I need to feed tangs nori?

Yes, daily. All tangs are primarily herbivorous and need vegetable matter. Nori sheets clipped to the tank, blanched zucchini or spinach, or dedicated algae-based pellet (Algae Wafers, NLS Marine, etc.) are mandatory.

Aquarium-keeping fundamentals

Whatever specific topic brought you here, four fundamentals govern long-term aquarium success: water quality, parameter stability, biological filtration, and species-appropriate husbandry. Skip any one and the others struggle to compensate.

Water quality: ammonia + nitrite at zero, nitrate under 30 ppm freshwater + 10 ppm reef. Test weekly with API or Salifert kits. Use our water parameter checker to score your readings against your tank type.

Parameter stability: stable wrong parameters beat fluctuating ideal parameters. Most fish tolerate a wide pH range if it's stable. Sudden swings of 0.4+ pH or 5+°F kill fish faster than chronic suboptimal values. Use temperature controllers (Inkbird) + automated dosing for consistency.

Biological filtration: the bacterial colony on your filter media + rock + substrate is the engine. Never replace all media at once. Use our filter turnover calculator to size correctly.

Species-appropriate husbandry: research adult size, territoriality, diet, and tankmate compatibility before purchase. Use our tank stocking calculator + compatibility guides.

Frequently asked questions

How long does an aquarium take to set up? 4-6 weeks for full cycling + first stocking. Use our cycle ETA calculator + how long does cycling take.

What's the best aquarium for beginners? 20-gallon long. Big enough for parameter stability, small enough for budget + space. See beginner picks.

How often should I do water changes? 25-30% weekly. See water change frequency Q&A + water change calculator.

Why does my fish keep dying? 5 leading causes: uncycled tank, wrong species pairings, no quarantine, undersized tank, neglected water-change schedule. See full diagnosis.

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