I've decided on a new plan... As my aquarium has been opentop, there has always been a possibility that my past fish MAY have jumped out and some rodent or something may have had them and thats why they have disapeared, so I have made myself a DIY cover for the top of my tank which consists of an acrylic frame with plastic pond netting tied down to it and fits on the support brackets on the inside of my tank. Once in place no fish should be able to jump out of the tank top.
So hopefully tommorow I plan on going out and getting myself a green/blue chromis or 2 as they are quite cheap and are also reputed as being very hardy. I am going to place them/it in the tank knowing perfectly well that they/it will not be able to jump out of the tank and see how they/it get on.
I'm only planing on buying 2 as I have heard they will survive better if there is more than one as they are shoaling fish? What do you think 1, 2 or more??
If I do indeed have a predator in the tank then I expect one fish to go missing followed a few days later by the other and this will confirm my suspicions! If this is indeed the case then I will have to move onto my plan of getting a predatory wrasse eg. cory of dragon to help me elliminate the problem.
It may seem cruel that I am using live fish as bait but but I believe it is necessary to confirm that I do have a predatory shrimp/crab in my tank for my knowldege and also the chromis dont cost to much and so wouldnt be too big a financial loss and (hopefully) they wont just die on me!
Let me know your feedback and advice.
I will keep everybody updated