Please note that when making a ONT/ONG transaction or when claiming ONG you will be charged with a 0.05 ONG network fee. This network fee is set by Ontology and can not be changed. This means that if you do not have any ONG yet you can not claim or make transactions.
When you do have ONG and are about to claim, make sure the claimable amount is higher than 0.05 ONG, otherwise you pay more in fees than what you will receive. Also please make sure that you always have 0.05 ONG left to pay for the next claim. Once you go below that 0.05 ONG you will need to buy extra ONG again on an exchange or elsewhere.
For more info please check this FAQ from Ontology