We do not the percent of your losses. If you have more than 80% - so just hold. You loss a lot and to fix this losses is not very correct. You can wait at least little market rising, and only than sell with small losses. But if you only have -20% now - so sell and do not think. Market will go a little deeper soon and you can buy more alts to your portfolio. But the best way in crypto now - not to buy alts and hold Bitcoin)