For a 20: best start with tough corals and inverts (with good lighting) because the best fish are fragile: smallest gobies, blennies
For a 30: again, starting with corals and inverts, graduating to larger gobies, blennies, maybe a clown pair but NO anemone until mature tank/hobbyist
For a 50: corals are fine, but so are blennies, gobies, fairy wrasses, dartfish [they jump]; clown pair (again, wait on nem), dwarf angel, etc. ALso good special-species tank; only 1 damsel in this size. Once you have a STRONG fuge going, one of the smallest dragonets, only one.
For a 75: pretty much same as a 50, but more variety.
For a 100: again, more variety, very smallest browsing tang species; multiple damsels ok, one of a kind; mandarin or scooter ok with fuge
150: more varieties; more species of tangs become viable; butterfly with extreme caution (fragile, and nippers); angels become viable (they eat coral and sponge);
200: again, larger species, more varieties.
Most of us WILL have more than one tank in a lifetime, and most of us don't start out with a 200 or larger. If what you would like to have doesn't fit the tank you have, don't get it--yet. Wait for that future tank. Meanwhile explore what will make a beautiful tank where you are.
Far from a comprehensive list, but you can kind of see the size cutoff points, and I hope it may help you figuring out what's cool to have---most who start the hobby don't even know the blenny and goby families, but they're the very best for the small tanks everybody starts with. As your skill and ambition increase (along with experience) you can look toward the tank o' yer dreams down the way...with a real likelihood of making it work and having your critters live.
The real small fish have about a 7-8 year lifespan; the larger ones, way longer: plan on that. Not quite that of koi, at 235 years---but still, ideally above a decade. It's like getting a dog or cat: you're in it for much longer when you get the larger species.
Hope this helps give you some ideas what you can do. And don't be scared of corals: they're living filters, help improve the water, and some of them (not the pricey ones, alas) grow like crabgrass given decent lighting and conditions.
For a 30: again, starting with corals and inverts, graduating to larger gobies, blennies, maybe a clown pair but NO anemone until mature tank/hobbyist
For a 50: corals are fine, but so are blennies, gobies, fairy wrasses, dartfish [they jump]; clown pair (again, wait on nem), dwarf angel, etc. ALso good special-species tank; only 1 damsel in this size. Once you have a STRONG fuge going, one of the smallest dragonets, only one.
For a 75: pretty much same as a 50, but more variety.
For a 100: again, more variety, very smallest browsing tang species; multiple damsels ok, one of a kind; mandarin or scooter ok with fuge
150: more varieties; more species of tangs become viable; butterfly with extreme caution (fragile, and nippers); angels become viable (they eat coral and sponge);
200: again, larger species, more varieties.
Most of us WILL have more than one tank in a lifetime, and most of us don't start out with a 200 or larger. If what you would like to have doesn't fit the tank you have, don't get it--yet. Wait for that future tank. Meanwhile explore what will make a beautiful tank where you are.
Far from a comprehensive list, but you can kind of see the size cutoff points, and I hope it may help you figuring out what's cool to have---most who start the hobby don't even know the blenny and goby families, but they're the very best for the small tanks everybody starts with. As your skill and ambition increase (along with experience) you can look toward the tank o' yer dreams down the way...with a real likelihood of making it work and having your critters live.
The real small fish have about a 7-8 year lifespan; the larger ones, way longer: plan on that. Not quite that of koi, at 235 years---but still, ideally above a decade. It's like getting a dog or cat: you're in it for much longer when you get the larger species.
Hope this helps give you some ideas what you can do. And don't be scared of corals: they're living filters, help improve the water, and some of them (not the pricey ones, alas) grow like crabgrass given decent lighting and conditions.
