Plenty Credit Union, a small community credit union serving Melbourne's north-east, will fold into Credit Union Australia, the two groups announced yesterday.With around $85 million in assets and running small operating losses, the credit union is taking the decision of more than 500 of its brethren over the last decade or so, and joining with a bigger mutual.What is unusual about the Plenty merger with CUA is that there have been few such decisions announced this year.Maritime, Mining & Power Credit Union, based in Sydney, earlier this year announced mergers with Reliance Credit Union and Gosford City Credit Union, so the run rate so far this year is only three.Small credit unions, no matter how good, find the compliance and support costs needed to remain independent a strain. APRA also continues to steer credit unions towards mergers.