We have suddenly discovered some eggs in our mixed tropical tank, attached to side of the fluval filter, which is attached to corner of 3 foot tank. They are currently a mixture of brown and white - more brown though, and approximately 50 I guess, and about the size of a pinhead each. Yesterday there seemed to be more than today so some have disappeared. Not only that, my filter is not as powerful as it was a few days ago, so I reckon some eggs have gone in the slits and may be clogging it up?

The only fish who show any "responsibility" or ownership for these eggs are two angelfish, who we didn't even realise were different sexes. We have also had them for years and this is a first. However, my fish books at home are not very detailed about their spawn and I have no idea about next steps, so to speak.

- How can I tell if they are definitely the angel fish's? (my fish books say they lay eggs on leaves and this is on the side of the filter, although we don't have many plants in tank.)
- how long will it take for them to hatch?
- why are some brown and some white?
- is there anything I should be doing?
- what about my filter slowly getting sluggish - I guess I can't clean my tank/filter until these are hatched?
- anything else I should know?

Thanks for any advice and apologies for my ignorance in these fishy fertility matters!