Note 9 - Stockholders' Equity - Summary of Stock Option Activity (Details)	6 Months Ended
	Sep. 30, 2025 $ / shares shares
Outstanding, option (in shares) | shares	14,000
Outstanding, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 15.1
Granted, option (in shares) | shares	0
Granted, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 0
Exercised, option (in shares) | shares	0
Exercised, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 0
Forfeited or expired, option (in shares) | shares	(1,500)
Forfeited or expired, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 50.6
Outstanding, option (in shares) | shares	12,500
Outstanding, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 10.8
Exercisable, option (in shares) | shares	12,500
Exercisable, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 10.8