The warm, inviting glow of that pricey tank in our homes or our favorite sea food restaurants can be a living, bubbling conversation piece. We treat the tanks and those in them more as decor than pets, which is probably a good thing. Most “pet” salt water fish don’t live long.

And to get that one tang, angelfish or clownfish, many many others had to die as they’re plucked from reefs, stunned with cyanide or rooted out with dynamite. Not pleasant to think about, but “The Dark Hobby” gets right in your face about this vast “trade” in fish collecting and reef-looting.

Paula Fouce’s film parks itself at ground zero in the “war on fish collecting,” Hawaii. It’s the place in the United States where such exotics have been treated as “inventory” by a handful of big aquarium supply companies, depleting the island’s reefs and seriously damaging the coral and dinging the snorkeling/diving tourism industry as it does.

You fly all the way out, rent a tank and day trip to a reef, and it’s as deserted as the brown lumps off the Florida Keys, which also used to teem with life.

We hear from biologists and Kapuna elders, from educators and Humane Society and PETA activists, and from people who were once “in the business” of exporting or selling tropical fish to America and the world’s aquariums. And we witness Hawaii’s battle over regulating or even banning the practice, a stumbling, years-long struggle to not let the Pearls of the Pacific turn into the ruined, lifeless reefs of the Philippines or the Greater Caribbean.

The fish who clean, groom and police the reefs are vital to their survival, the experts here argue. They’re not just “instinctive” creatures, but animals with self-awareness and “biographies.”

Just watch “My Octopus Teacher” as your homework.

The simple truth, one former industry insider admits, is that “there’s not enough value put on their lives” to stop this in much of the world.

Fouce (“Song of the Dunes: Search for the Original Gypsies” and “No Asylum: The Untold Chapter of Anne Frank’s Story”) builds her film around the efforts of Hawaiian Robert Wintner, aka “Snorkel Bob,” a diver, reef-lover and outspoken activist in this long struggle to stop the looting of Hawaii’s natural resources by bottom-feeing wildlife dealers.

“All you need is $50 and a pulse” to get a license to harvest reef fish, Wintner complains here, there and everywhere. The reefs are being damaged, the experience of diving on them ruined and the island’s patrimony sacrificed for “an amusement industry.”

Those fish belong on the reef, Hawaiian elder Willy Kaupiko complains. “Don’t take our fish and put them in an aquarium in New York or Tennessee!”

The film doesn’t seek “balance” on this story, just snippets of a Youtube influencer talking about her tanks and fish that outgrow it. The collectors have been known to attack divers photographing their looting. And no wonder, considering the fact that like baby seal clubbers and Japanese dolphin slaughterers, they know they’re doing something wrong.

A quick DuckDuckGo search reveals the vast subculture of collectors and aquarium aficionados who aren’t giving this side of their hobby a lot of thought. As “in your face” as the arguments presented here are, a more confrontational filmmaker would have filmed Snorkel Bob approaching and debating such enthusiasts, the way PETA people get after puppy mill customers.

But there aren’t really two sides to this, even as we hear discussions of “buying out” people who have made this trade their livelihood, even as we see legislation move slowly, face gubernatorial vetoes and court tests as the reefs grow more barren and brown.

Heck, even the global explosion in destructive lionfish populations is attributable to collecting and tanking tropical fish.

“The Dark Hobby” has rhetorical “solution step” answers to the vexing problems it presents here, the wildlife sanctuaries that are cropping up in the seas off Hawaii, and the one totally surrounding the island of Cuba, a reef in the process of healing that could position the country to be the dive tourism capital of the world unless the rest of the world takes similar action.

There are “reef cams” for those who want that “live fish” experience in their home. “Buy an HDTV” Snorkel Bob half-jokes. Tune in to say, Deerfield Beach, Florida’s reef cam.

Activists are missing the boat if they aren’t attacking this problem on the consumer end. Granted, shaming tropical bird owners hasn’t saved their souls, but fish tank fanatics? They should be easier to reach.

Just show them the dusty, unused, long-stored tank you find at any given yard sale on any street in America and ask them if they really have to have one?

Aquariums can be lovely, if you can stand the noise, smell and grim business of cleaning them or dealing with the deaths of the “pets” you confine in them.

A few testimonials about the ordeal of trying to unload the damned thing when you’re tired of the cleaning, maintenance and constant refreshing of the living critters you keep in it would do more to kill off this “Dark Hobby” than anything else.

MPA Rating: unrated

Cast: Robert Wintner aka “Snorkel Bob,” Jessica Wooley, Yvonne Ware, Jonathan Balcombe, Gail Grabowsky, Rene Umberger

Credits: Directed by Paula Fouce, scripted by Paula Fouce, William Haugse. A Rhino Films release.

Running time: 1:13