Gameview Studios, a pioneer in using virtual currencies and in-app payments that was later acquired by Japan’s DeNA, said its top title Tap Fish surpassed 10 million downloads today. The app, which lets players decorate virtual fish tanks, consistently ranks among the top five highest-grossing titles targeted at kids in the Apple store.

Rizwan Virk, who founded the company and is an avid angel in the space through his investments in Tapjoy and analytics company Apsalar, shared a few of his reflections with us on how the app industry has changed in the last year.

He said despite the acquisition six months ago, Gameview still maintains a great deal of operational independence.

“Honestly, not that much has changed. They bought us right around when they got ngmoco:) and we operate as a wholly-owned subsidiary,” he said. Virk says more attention has gone into metrics since the acquisition. DeNA has stressed following engagement numbers, like how many users return to a title after downloading it.

“Before the acquisition, we were basically flying by the seat of our pants,” he said. “Engagement is a metric the industry probably isn’t measuring as well as it should since so many developers are doing incentivized installs.”

The company has also focused on newer games in recent weeks like Tap Jurassic, which is ranked ninth among free iPhone games in the U.S. Gameview plans to bring its existing titles to Android as well, which became the leading smartphone operating system, according to Comscore yesterday. Virk estimates that across Gameview’s entire suite of games, the company has seen 20 million downloads.

Like many other developers, the company has used two currencies to monetize the game — one as an engagement currency that’s awarded to players and the other as a paid, premium currency. In Tap Fish, it’s called Fish Bucks. While gamers can buy the currency in packets worth all the way up to $99.99, most buy at the $1.99 price point.

Gameview has also experimented with several younger pay-per-install networks beyond Tapjoy, including Flurry, Mdotm and G6 Pay. AdMob, he’s found, has been too expensive when he calculates out the effective cost-per-install. Even as more mobile developers pursue the pay-per-install route to promote their games, the arrival of all these new networks has helped keep costs down.

“They have a deflationary effect on the price,” he said. “The price of advertising a new game is going to get more expensive and people will need to rely on other channels like word of mouth, blogs and reviews,” he said.

Virk is starting to experiment with ngmoco:)’s Plus+ network and hopes to port Gameview’s titles to DeNA’s Mobage soon. DeNA is gearing up to take Mobage Town, its mobile gaming network, worldwide later this spring through partnerships with device manufacturers like Samsung.

Virk was a bit bearish on Facebook for user acquisition. ”Nobody’s been able to straddle Facebook and mobile platforms really successfully yet,” he said. “Angry Birds is going to try, but we’re skeptical of that.” He added that Tap Fish’s user base actually doesn’t really overlap all that much with Facebook since many players are children and their parents.